I have the same problem like you guys, it has been like that for the past 2 YEARS, no answere.
The only think you can do is get new MT rb with User Manager for each Hot Spot. Or teach yourself freeRadius,
Check all my post in the past to find more info about it. here is one recent link. http://forum.mikrotik.com/t/user-manager-doesnt-accept-aaa-of-3-hotspots-on-one-750-l4/52079/1
Any one can help, how about SUPPORT here? would be nice ?
thx