pg_stat_activity.client_addr sometimes null for host connections - Mailing list pgsql-admin

I have a process that regularly queries pg_stat_activity for user connections.
Today I noticed an error because sometimes client_addr is null for some user
connections.  pg_hba.conf only allows host connections.  So client_addr should
not be null according to [0].  pg_stat_activity is queried as superuser who
should see client_addr for all connections, not just his own.

This is on v12.14 on Windows Server (regular EnterpriseDB install).  Is this a
known issue or just an undocumented corner case?

[0] https://www.postgresql.org/docs/12/monitoring-stats.html#PG-STAT-ACTIVITY-VIEW

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Erik