Sync music leads to file lock

I sync my files to my local machine (linux mint). Including a music folder. I add this synced-music folder as standard folder for creating a library in my music program (rhytmbox, clementine)
After that, my nc-client starts to give the error message, that “music-file” is locked, existing lock on file: 3 locks.

what can I do, to have my music locally synced and still be able to add them to my music library?

I already deleted and uploaded everything, but it keeps happening.

System:
Kernel: 5.15.0-107-generic x86_64 bits: 64 Desktop: Cinnamon 6.0.4
Distro: Linux Mint 21.3 Virginia
NC-Client: 3.12.3