Forum user reports that when a MUC room has a group ACL set, this group ACL does not get modified when a user is added to a group. The user has to restart the server to get the ACL to update properly.
I experience the exact same issue in my 3.10.2 environment. As a workaround I just remove groups from a MUC's ACL and re-add it. This will kick everyone out of the room, but it will work afterwards.
OK, confirmed this is a caching issue in the GroupAwareMap implementation. Investigating options to clear the cache when a corresponding Group is updated; will report back shortly.
Currently evaluating additional discussion (via Github contribution) about removing secondary caching entirely.
Updated secondary cache to manage group names only (rather than group instances) to enable group retrieval from the primary cache, and also avoid creating orphaned groups. PR under review.