.m4a Music files not showing up on iPhone Apple Music App

I have been saving .m4a files of older music to my phone to listen to on the go. However, sometime late last year, the .m4a files that I listened to are not showing up on my Apple Music App. They are synced from my mac, and they are seen fine on the desktop Apple Music App.

I've verified that it's only the .m4a files which don't show up by looking at the filetypes inside User/Music/Music/Media/Music for each of the artists and comparing it to my phone App Library.

I've verified that it is not a syncing issue my looking at the actual contents of my iPhone in the Settings App, at Music -> Downloaded Music, where the songs and artists of the missing albums are all shown to be on my phone.

This issue has just about halved my music library. How do I fix this issue? Is there some setting which was flipped as of ios 17? If so, how can I make it so that the App can recognize .m4a files again? At this point, I'm considering just grepping through my music files and using ffmpeg to convert all of the files to .mp3 files, as long and inefficient it may be.