MySQL one file per table not working
First of all, innodb_file_per_table is enabled by default for MySQL 8.
If you want to know what tables are sitting in ibdata1, run the following query
select * from information_schema.innodb_tables;

This will inform you about each table and what tablespace it resides in
EXAMPLE
I spun of a vagrant lab that runs MySQL 8.0.17
I loaded the KJV of the Bible and added a fulltext index
Here is the output of the query I mentioned
mysql&gt; select * from information_schema.innodb_tables;
+----------+-----------------------------------------------------+------+--------+------------+------------+---------------+------------+--------------+
| TABLE_ID | NAME                                                | FLAG | N_COLS | SPACE      | ROW_FORMAT | ZIP_PAGE_SIZE | SPACE_TYPE | INSTANT_COLS |
+----------+-----------------------------------------------------+------+--------+------------+------------+---------------+------------+--------------+
|     1025 | mysql/db                                            |  161 |     25 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1026 | mysql/user                                          |  161 |     54 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1027 | mysql/default_roles                                 |  161 |      7 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1028 | mysql/role_edges                                    |  161 |      8 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1029 | mysql/global_grants                                 |  161 |      7 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1030 | mysql/password_history                              |  161 |      7 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1031 | mysql/func                                          |  161 |      7 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1032 | mysql/plugin                                        |  161 |      5 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1054 | mysql/help_topic                                    |  161 |      9 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1055 | mysql/help_category                                 |  161 |      7 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1057 | mysql/help_relation                                 |  161 |      5 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1036 | mysql/servers                                       |  161 |     12 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1037 | mysql/tables_priv                                   |  161 |     11 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1038 | mysql/columns_priv                                  |  161 |     10 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1056 | mysql/help_keyword                                  |  161 |      5 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1040 | mysql/time_zone_name                                |  161 |      5 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1041 | mysql/time_zone                                     |  161 |      5 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1042 | mysql/time_zone_transition                          |  161 |      6 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1043 | mysql/time_zone_transition_type                     |  161 |      8 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1044 | mysql/time_zone_leap_second                         |  161 |      5 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1045 | mysql/procs_priv                                    |  161 |     11 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1046 | mysql/component                                     |  161 |      6 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1047 | mysql/slave_relay_log_info                          |  161 |     12 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1048 | mysql/slave_master_info                             |  161 |     31 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1049 | mysql/slave_worker_info                             |  161 |     16 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1050 | mysql/gtid_executed                                 |  161 |      6 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1051 | mysql/server_cost                                   |  161 |      7 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1052 | mysql/engine_cost                                   |  161 |      9 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1053 | mysql/proxies_priv                                  |  161 |     10 | 4294967294 | Dynamic    |             0 | General    |            0 |
|     1058 | sys/sys_config                                      |   33 |      7 |          1 | Dynamic    |             0 | Single     |            0 |
|     1101 | bible/verses                                        |   33 |      8 |         44 | Dynamic    |             0 | Single     |            0 |
|     1102 | bible/fts_000000000000044d_being_deleted            |   33 |      4 |         45 | Dynamic    |             0 | Single     |            0 |
|     1103 | bible/fts_000000000000044d_being_deleted_cache      |   33 |      4 |         46 | Dynamic    |             0 | Single     |            0 |
|     1104 | bible/fts_000000000000044d_config                   |   33 |      5 |         47 | Dynamic    |             0 | Single     |            0 |
|     1105 | bible/fts_000000000000044d_deleted                  |   33 |      4 |         48 | Dynamic    |             0 | Single     |            0 |
|     1106 | bible/fts_000000000000044d_deleted_cache            |   33 |      4 |         49 | Dynamic    |             0 | Single     |            0 |
|     1107 | bible/fts_000000000000044d_00000000000000cd_index_1 |   33 |      8 |         50 | Dynamic    |             0 | Single     |            0 |
|     1108 | bible/fts_000000000000044d_00000000000000cd_index_2 |   33 |      8 |         51 | Dynamic    |             0 | Single     |            0 |
|     1109 | bible/fts_000000000000044d_00000000000000cd_index_3 |   33 |      8 |         52 | Dynamic    |             0 | Single     |            0 |
|     1110 | bible/fts_000000000000044d_00000000000000cd_index_4 |   33 |      8 |         53 | Dynamic    |             0 | Single     |            0 |
|     1111 | bible/fts_000000000000044d_00000000000000cd_index_5 |   33 |      8 |         54 | Dynamic    |             0 | Single     |            0 |
|     1112 | bible/fts_000000000000044d_00000000000000cd_index_6 |   33 |      8 |         55 | Dynamic    |             0 | Single     |            0 |
|     1113 | bible/books                                         |   33 |      5 |         56 | Dynamic    |             0 | Single     |            0 |
|     1150 | ft_db/ft_test_innodb                                |   33 |      6 |         93 | Dynamic    |             0 | Single     |            0 |
|     1151 | ft_db/fts_000000000000047e_being_deleted            |   33 |      4 |         94 | Dynamic    |             0 | Single     |            0 |
|     1152 | ft_db/fts_000000000000047e_being_deleted_cache      |   33 |      4 |         95 | Dynamic    |             0 | Single     |            0 |
|     1153 | ft_db/fts_000000000000047e_config                   |   33 |      5 |         96 | Dynamic    |             0 | Single     |            0 |
|     1154 | ft_db/fts_000000000000047e_deleted                  |   33 |      4 |         97 | Dynamic    |             0 | Single     |            0 |
|     1155 | ft_db/fts_000000000000047e_deleted_cache            |   33 |      4 |         98 | Dynamic    |             0 | Single     |            0 |
|     1156 | ft_db/fts_000000000000047e_0000000000000107_index_1 |   33 |      8 |         99 | Dynamic    |             0 | Single     |            0 |
|     1157 | ft_db/fts_000000000000047e_0000000000000107_index_2 |   33 |      8 |        100 | Dynamic    |             0 | Single     |            0 |
|     1158 | ft_db/fts_000000000000047e_0000000000000107_index_3 |   33 |      8 |        101 | Dynamic    |             0 | Single     |            0 |
|     1159 | ft_db/fts_000000000000047e_0000000000000107_index_4 |   33 |      8 |        102 | Dynamic    |             0 | Single     |            0 |
|     1160 | ft_db/fts_000000000000047e_0000000000000107_index_5 |   33 |      8 |        103 | Dynamic    |             0 | Single     |            0 |
|     1161 | ft_db/fts_000000000000047e_0000000000000107_index_6 |   33 |      8 |        104 | Dynamic    |             0 | Single     |            0 |
+----------+-----------------------------------------------------+------+--------+------------+------------+---------------+------------+--------------+
55 rows in set (0.00 sec)

mysql&gt; desc information_schema.innodb_tables;
+---------------+---------------------+------+-----+---------+-------+
| Field         | Type                | Null | Key | Default | Extra |
+---------------+---------------------+------+-----+---------+-------+
| TABLE_ID      | bigint(21) unsigned | NO   |     |         |       |
| NAME          | varchar(655)        | NO   |     |         |       |
| FLAG          | int(11)             | NO   |     |         |       |
| N_COLS        | int(11)             | NO   |     |         |       |
| SPACE         | bigint(21)          | NO   |     |         |       |
| ROW_FORMAT    | varchar(12)         | YES  |     |         |       |
| ZIP_PAGE_SIZE | int(11) unsigned    | NO   |     |         |       |
| SPACE_TYPE    | varchar(10)         | YES  |     |         |       |
| INSTANT_COLS  | int(11)             | NO   |     |         |       |
+---------------+---------------------+------+-----+---------+-------+
9 rows in set (0.00 sec)

mysql&gt;

Please note that any table whose space value is 0, resides in the ibdata1. It says to in the MySQL 8.0 Docs about INFORMATION_SCHEMA.INNODB_TABLES;
At the moment, there are no tables in ibdata1.
Let's see If I can inject one into ibdata1.
mysql&gt; use bible
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql&gt;
mysql&gt;
mysql&gt; set global innodb_file_per_table = 'OFF';
Query OK, 0 rows affected (0.00 sec)

mysql&gt; create table injection (id int not null auto_increment, name varchar(20), primary key (id));
Query OK, 0 rows affected (0.04 sec)

mysql&gt; insert into injection (name) values ('Hello, World !!!');
Query OK, 1 row affected (0.01 sec)

mysql&gt; select * from injection;
+----+------------------+
| id | name             |
+----+------------------+
|  1 | Hello, World !!! |
+----+------------------+
1 row in set (0.00 sec)

mysql&gt;

OK, now let's check information_schema
mysql&gt; select * from information_schema.innodb_tables where space = 0;
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
| TABLE_ID | NAME            | FLAG | N_COLS | SPACE | ROW_FORMAT | ZIP_PAGE_SIZE | SPACE_TYPE | INSTANT_COLS |
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
|     1162 | bible/injection |   33 |      5 |     0 | Dynamic    |             0 | System     |            0 |
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
1 row in set (0.00 sec)

mysql&gt;

TADA !!!
OK, so now go run
select * from information_schema.innodb_tables where space = 0;

If you don't see any rows returned, then you have nothing in ibdata1.
WHAT IF I STILL HAVE TABLES IN ibdata1?
If you are starting brand new in MySQL. You should not have this problem from the beginning. Notwithstanding, let's say you have this situation in MySQL 8.0. How to you do yank the table out of ibdata1 ???
Let's try ALTER TABLE ... ENGINE=InnoDB
Unfortunately, you cannot perform a NULL ALTER like before:
mysql&gt; select * from information_schema.innodb_tables where space = 0;
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
| TABLE_ID | NAME            | FLAG | N_COLS | SPACE | ROW_FORMAT | ZIP_PAGE_SIZE | SPACE_TYPE | INSTANT_COLS |
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
|     1162 | bible/injection |   33 |      5 |     0 | Dynamic    |             0 | System     |            0 |
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
1 row in set (0.00 sec)

mysql&gt; set global innodb_file_per_table = 'ON';
Query OK, 0 rows affected (0.00 sec)

mysql&gt; alter table bible.injection engine=InnoDB;
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql&gt; select * from information_schema.innodb_tables where space = 0;
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
| TABLE_ID | NAME            | FLAG | N_COLS | SPACE | ROW_FORMAT | ZIP_PAGE_SIZE | SPACE_TYPE | INSTANT_COLS |
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
|     1163 | bible/injection |  161 |      5 |     0 | Dynamic    |             0 | System     |            0 |
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
1 row in set (0.00 sec)

mysql&gt;

You could get away with this in MySQL 5.7 and back. For MySQL 8.0, the temp table used maintains the table's current tablespace metadata.
Let's try CREATE TABLE LIKE
mysql&gt; create table bible.injection2 like bible.injection;
Query OK, 0 rows affected (0.03 sec)

mysql&gt; select * from information_schema.innodb_tables where space = 0;
+----------+------------------+------+--------+-------+------------+---------------+------------+--------------+
| TABLE_ID | NAME             | FLAG | N_COLS | SPACE | ROW_FORMAT | ZIP_PAGE_SIZE | SPACE_TYPE | INSTANT_COLS |
+----------+------------------+------+--------+-------+------------+---------------+------------+--------------+
|     1163 | bible/injection  |  161 |      5 |     0 | Dynamic    |             0 | System     |            0 |
|     1164 | bible/injection2 |  161 |      5 |     0 | Dynamic    |             0 | System     |            0 |
+----------+------------------+------+--------+-------+------------+---------------+------------+--------------+
2 rows in set (0.00 sec)

mysql&gt; select @@global.innodb_file_per_table;
+--------------------------------+
| @@global.innodb_file_per_table |
+--------------------------------+
|                              1 |
+--------------------------------+
1 row in set (0.00 sec)

mysql&gt;

OK Ouch !!!. That pesky tablespace metadata gets dragged around like luggage.
Let's try ALTER TABLE ... TABLESPACE=innodb_file_per_table
Here we go ...
mysql&gt; create table bible.injection2 like bible.injection;
Query OK, 0 rows affected (0.03 sec)

mysql&gt; select * from information_schema.innodb_tables where space = 0;
+----------+------------------+------+--------+-------+------------+---------------+------------+--------------+
| TABLE_ID | NAME             | FLAG | N_COLS | SPACE | ROW_FORMAT | ZIP_PAGE_SIZE | SPACE_TYPE | INSTANT_COLS |
+----------+------------------+------+--------+-------+------------+---------------+------------+--------------+
|     1163 | bible/injection  |  161 |      5 |     0 | Dynamic    |             0 | System     |            0 |
|     1164 | bible/injection2 |  161 |      5 |     0 | Dynamic    |             0 | System     |            0 |
+----------+------------------+------+--------+-------+------------+---------------+------------+--------------+
2 rows in set (0.00 sec)

mysql&gt; select @@global.innodb_file_per_table;
+--------------------------------+
| @@global.innodb_file_per_table |
+--------------------------------+
|                              1 |
+--------------------------------+
1 row in set (0.00 sec)

mysql&gt; ALTER TABLE bible.injection2 TABLESPACE=innodb_file_per_table;
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql&gt; select * from information_schema.innodb_tables where space = 0;
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
| TABLE_ID | NAME            | FLAG | N_COLS | SPACE | ROW_FORMAT | ZIP_PAGE_SIZE | SPACE_TYPE | INSTANT_COLS |
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
|     1163 | bible/injection |  161 |      5 |     0 | Dynamic    |             0 | System     |            0 |
+----------+-----------------+------+--------+-------+------------+---------------+------------+--------------+
1 row in set (0.00 sec)

mysql&gt; ALTER TABLE bible.injection TABLESPACE=innodb_file_per_table;
Query OK, 0 rows affected (0.18 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql&gt; select * from information_schema.innodb_tables where space = 0;
Empty set (0.00 sec)

mysql&gt;

TADA !!!
CONCLUSION
If you suspect any tables are in ibdata1, find them with
select * from information_schema.innodb_tables where space = 0;

Then just run
ALTER TABLE mydb.mytable TABLESPACE=innodb_file_per_table;

Please remember: The default innodb_file_per_table is ON.
No need to mysqldump and reload.
If you are attempting to shrink ibdata1, you will have load data into a brand new installation. You cannot just delete ibdata1 like you could in MySQL 5.5 and back. MySQL 5.6 + has innodb tables in the mysql schema database. So, you cannot play the same file manipulation games. MySQL 8.0 now demands a lot more respect from a DBA.