iTunes Library on NAS is partially destroyed

I have moved my iTunes Library to my NAS Storage. Everything worked fine.

Until more and more Tracks got scrambled: The location of the file now does not point to the library storage anymore but to a Time Machine location.

I have my Time Machine backups on the same NAS but a different mount point / file system.

Here's an example:

Good file location: /Volumes/music/iTunes/Music/A-HA/Diverse/Move to memphis.mp3

Bad file location: /Volumes/timemachine/MacBook Air.sparsebundle/bands/2440

What strikes me:

A lot of tracks (maybe all?) with a defect location is included in the sync with my iPhone / iPad.

Example: if I have an album from which only one track is on my iPhone, this tracks location is bad, the others are good.

Does anyone have a singular problem – and a solution for it?

Please help!

Thanx, Goetz