Tidal Library Synchronisation will not end

I only see the beautiful Roon (loading) Symbol in my overview with the synchronisation circle in the upper right turning and turning and turning …

This has occurred since I recently added 1570 files to my approx. 102 k file library.

I currently have Roon Core running on a QNAP NAS. If I disable Tidal, everything works fine.

Any ideas?