Finally, the last suggestion worked!
Seems like the full path or part of the path were causing issues, using only one word from the path did it.
Explanation for varying paths in xml:
If i chose "browse path" in library node editor, i get this selection.
"Volume" points directly to the HDD while "Root filesystem" ofc points to / = root.
I tried both paths in the xml, both were empty.
But now, using "contains" and only one word, it works.
Maybe the slashes or the underscores in "media_rw"/"_Soundtracks_" were causing the issue.
But then again, it works when i just put "_Soundtracks_" as "path contains".
Hm.
Either way, thx very much