Can't Access Some Local File Music on Phone

[Saediga]

Plan

Premium

Country

Australia

Device

Samsung galaxy S9

Operating System

Whatever the latest update one is. Sorry, not sure how to check.

My Question or Issue

So I got a soundtrack filled with some songs from one of my favourite movies. None of the songs are on Spotify, I already checked, and there are no titles like them and I don't think the artist is on there either. Pop the music into my music folder, no problem, works fine for a few weeks and then last week two of the songs grey out but only when I'm listening from the Liked Songs playlist on my phone.  On my computer it works fine. On the Local Files playlist they work fine despite being grayed out, but I need them to y'know not be grayed out so I can move them into a new playlist from time to time and it's really annoying.

Anything I can do to fix this?