Local Files not syncing to iPhone

[JuliusSneezer04]

I'm a heavy Spotify user on my iPhone 6S Plus but there's always been the hitch of syncing files on my laptop to my iPhone. I've followed all mentioned steps on other threads with no luck. I have a playlist with only my local files on my desktop, but on my phone, even though it shows how many songs there are in the playlist, it doesn't show any songs when I open the playlist.

Looking for a quick fix, thanks!

(Also, forgive me for the poor quality of the photos attached)