Synchronize local files to windows phone doesn't work

[Opusretis]

I tried to synchronize local files from my pc to my windows phone 10.
Unfortunately I struggled. I can add some files from my local hard drive to the local files collection and add them to a playlist.

On my Windows Phone I tried to make the same playlist offline available. My Windwos Phone is downloading all spotify songs shows then 100% Status and holds this state for ever. Correctly it should show the Offline Icon after it reaches 100%
The songs from my Pc's local drive do not appear on the Windows Phone.

[12129000667]

That happens to me but with an Android phone... pls help i want to play Tool on playlist.