Can't get access to streaming replication stats in PostgreSQL

I have streaming replication which I need to monitor. So there is a special user for Zabbix. I don't want to use pg_mongz and decided to set my own queries to pg_catalog schema's view pg_stat_replication to get replication state.

When I use query:

select * 
from pg_stat_replication;

it returns replication state record for admin. But when I logged in as monitoring user it returns just:

pid, usesysid, usename, application_name

So such parameters as client_addr, client_hostname, client_port, backend_start, state, sent_location, write_location, etc. are empty.

First I granted rights to my user on schema and tables:

grant usage on schema pg_catalog to usrmonitor;
grant select on all tables in schema pg_catalog to usrmonitor;

but it didn't help. When I looked at view I found that query uses functions and granted execution:

grant execute on function pg_stat_get_wal_senders() to usrmonitor;
grant execute on function pg_stat_get_activity(integer) to usrmonitor;

But the select query still returns empty columns. What maybe the problem?