I'm facing same issue and can't find any solution. Hotspot disable & enable solves the problem.
Have you found any workaround on this.
Thanks for tip. What's to send (to client) is user is already good for accounting (aka I don't want disconnect)?You need to send DM (disconnect message).
You have to connect all LANs to one routerboard (one with the hotspot) and make a bridge with ether or WLANs you need to autenticate, then the hotspot is installed in this interface bridge.