SQLDeveloper: Unable to desc a table that exists
This must be because of MYTABLE being a synonym of a synonym, which is not supported on SQL Developer 4.1.3(must be a bug). Reference

I have three users user3, user2 and user1

SQL&gt; conn user3/user3
Connected.
SQL&gt; create table mytable(id number);

Table created.

SQL&gt; grant select on mytable to user2 with grant option;  

Grant succeeded.

SQL&gt; conn user2/user2
Connected.
SQL&gt; create synonym mytable for user3.mytable;

Synonym created.

SQL&gt; grant select on mytable to user1;

Grant succeeded.

SQL&gt; conn user1/user1
Connected.

SQL&gt;  create synonym mytable for user2.mytable;

Synonym created.

SQL&gt; desc mytable;
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                                                 NUMBER

SQL&gt; conn / as sysdba       
Connected.
SQL&gt; select table_name from dba_all_tables where table_name='MYTABLE';

TABLE_NAME
------------------------------
MYTABLE

SQL&gt; select owner from dba_tables where table_name='MYTABLE';

OWNER
------------------------------
USER3


Now try to describe it on SQL Developer.

desc mytable;

ERROR: object MYTABLE does not exist