Local files added to playlist but isn't shown on iphone

[FrustratedCacti]

I have local files I want to play on my iPhone. I added them to the playlist... The playlist is shown on my iphone but NO SONGS are there, none. I tried checking all the settings and various forums in here, but people only have problems with sync not songs not showing up.
So when I go into the playlist, (on the same wifi and both apps are open) it says: want to add songs to this playlist? like a new playlist that's empty.
It's frustrating! I tried installing the latest versions and restarting etc.
(btw I have premium)
Hope anyone can help!