I have the same problem. There are no errors in the prosody log.
When I make a log output in the beginning of the mod_muc_max_occupants.lua file, it will be shown, but when a add a log output in the check_for_max_occupants function, it doesn’t work. It seems that the event “muc-occupant-pre-join” is not fired an so the function isn’t called.
My prosody version was 0.10. Now I have installed prosody-trunk 747, but it doesn’t work:
I have set muc_max_occupants = 2, but only one participant can join the meeting.
I get following error: Traceback[c2s]: /usr/lib/prosody/util/cache.lua:66: table index is nil
I have set storage to null, but the error is still there.