For some reason the by APC delivered software is supressing WMI. This is blocking windows to identify any UPS as a battery, thus OPMONis will not work properly, because it is impossible find the UPS.
At the moment the only solution is to reinstall the original driver by windows, which will unfortunately also block the possibility to use some features the APC software is delivering ( self-test, runtime-tests ).
A step by step solution for reactivating the original windows driver you can find here.
Probably now the APC software will complain that it cannot find the UPS, but this will not effect your system or your UPS security in any way.
The original APC drivers though can be reactivated at anytime without a problem, even on running systems if needed.