Postgres replication views I see some discrepancies between two views in postgres as to replication and lag time.

By this query, clearly replication is up:

9.5.6.11

postgres=# select client_addr, sent_location, replay_location from pg_stat_replication where application_name = 'walreceiver';
  client_addr   | sent_location | replay_location
----------------+---------------+-----------------
 172.yyy.yyy.213  | 1C/2B5732F8   | 1C/2B5732F8
 10.xxx.xxx.195 | 1C/2B5732F8   | 1C/2B5732F8
 10.xxx.xxx.196 | 1C/2B5732F8   | 1C/2B5732F8


10.1

postgres=# select client_addr, sent_lsn, replay_lsn from pg_stat_replication where application_name = 'walreceiver';
 client_addr  |  sent_lsn  | replay_lsn
--------------+------------+------------
 10.qqq.qqq.44 | 1/8C000140 | 1/8C000140


But when look for the lag time:

9.5.6.11

postgres-# SELECT pg_last_xlog_receive_location() ,  pg_last_xlog_replay_location() ,  now() ,  pg_last_xact_replay_timestamp();
 pg_last_xlog_receive_location | pg_last_xlog_replay_location |              now              | pg_last_xact_replay_timestamp
-------------------------------+------------------------------+-------------------------------+-------------------------------
                               |                              | 2018-05-10 04:19:38.079161-04 |


10.1

postgres=# SELECT pg_last_wal_receive_lsn() ,  pg_last_wal_replay_lsn() ,  now() ,  pg_last_xact_replay_timestamp();
 pg_last_wal_receive_lsn | pg_last_wal_replay_lsn |              now              | pg_last_xact_replay_timestamp
-------------------------+------------------------+-------------------------------+-------------------------------
                         |                        | 2018-05-10 04:29:21.730089-04 |


There are no info..
What am I missing?
It looks like you are running the 2nd set of queries on the master.  Those functions need to be run on the replica, not the master.