I noticed last week the my UPS Binding thing was offline. When I check the Pi4B running openHABian which runs openHAB and NUT, there was an error that the various nut services had failed due to a file in /etc/nut/ not existing. (Unfortunately, by the time I got around to troubleshooting today the journalctl and other log files had rotated and I can’t find the actual error on the system.
I tried rebooting the Pi. Still NUT services didn’t work.
I next tried removing and reinstalling (sudo apt-get purge nut followed by sudo apt-get install nut.
After that, it worked. Not sure what the problem was. Probably something I fiddled with that I didn’t mean to. Regards, just wanted to share with future travelers on this road that my mysterious problem was solved this way.