Look for this line in the controller config:
rei-off-channel-scanning = ENABLED
IF it is set as disabled, the AP errors on "Bands to scan" and "Channels to scan" when it tries to initiate a scan. There is no where in the controller to set the setting (that I have found,) so a find/replace of the config file will be necessary. You will change that line multiple times.
Just something to check.