Does this master controller terminate any APs, or is a dedicated master? Run the following from the CLI to see if the local controllers are talking to the master to pass along the appropriate information.
show switches
show switches summary
Also, I know you already checked for mobility managers, but run the following to make sure the master is set for wms:
show wms general
Look for
wms-on-master enable
Lastly, did anything change that you are aware of? Upgrades? Reboots? Config changes?
show audit-trail