New computer is trying to connect to hotspot - MAC authentification is proceeded at first with negative result, of course. I added MAC address then to userman, but it was not working - it seems like userman is remembering the MAC address as failed and is not trying to authentificate client anymore.

Only solution I've find is to restart hotspot - but I don't like this at all, because all active users are disconnected. Is there a better solution? Or, could the problem be solved in the next version?

I've solved this problem. After creating new MAC address user I have to delete it's MAC address from list Hotspot -> Hosts. Then it is working without restarting.