As of b42fafab, some methods in the MUC module call iq.send() without any callback. The call to this function returns a future when no callback is provided, that is never awaited, so nothing actually happens (see comment below).

• configure_room
• destroy
• set_affiliation
• set_role
• get_room_config
• cancel_config
• set_room_config

It's fine though when the future is returned, but this is only the case in get_users_by_affiliation.