Songs that I add to playlists are not syncing

So here's the problem.. I have Apple Music and it works fine within all my devices, with the exceptions of playlists, if I create a playlist on my phone it does sync to iTunes on my Mac, but the songs I add to it doesn't.

I've tried creating the playlist, wait for it to be synced to iTunes before adding one song but when I add the song it doesn't make it through. If I add a couple of songs at the same time some of them will sync but not all of them.. Any idea why this could happen?

Any help is highly appreciated :)