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! 

(Just realized that i posted this in the android-help sorry 😕 )