Resources window w/ my files stays empty

I use OmniOutliner in combination with OmniPresence (all newest version) to sync files with my mobile devices.
But the resources window on MacOS stays empty. I added the OP folder in OO but it stays empty.
The files get updated via OP (no matter where, MacOS, iOS and iPad).
Even “Used Files” (don’t know the exact English translation) stays empty - after opening files.
Any ideas?
Thank you,

PS: Strange behaviour - Command-I to get the Informations-window for a OO file (abc.ooutline) in Finder ends in the beachball, I have to restart Finder. Spacebar to get a QuickView works. Also opening the files works.