Local songs on PC are not getting synchronized on my android smartphone

[Colonnial]

I don't know why but suddenly my local songs I added to a playlist on my PC cannot be played on my smartphone.
The songs are shown on my smartphone, but in grey. When trying to play them on my smartphone a notification appears that spotify cannot play this track, yet, since it is not available on my my mobile.
I even added it by hand to the local storage. But nevertheless, it is not working.

[Joan]

Hi there @Colonnial,

Thanks for reaching out. Try performing a clean reinstall on both PC and your phone. Then, re-add the tracks and try again. Make sure the files are of supported file extensions and that they are from legitimate sources, see here.

Hope this helps.