Only the last 25 messages are loaded with XMPP MAM
When I tested XMPP MUC with MAM on localhost, I see that only the last 25 messages are loaded. The rest are ignored. I couldn't grep for 25, may be it's just random, but the count is consistently 25 (of which some are NULL). Interestingly, If I remove
chatty_history_add_message in chatty-xep-0313.c, all pending messages are loaded. It could be that writing to db is blocking something.