Music disappeared after upgrade from iOS 17 to iOS 18.1

Yesterday I upgraded my 13 mini from iOS 17 to iOS 18.1. After doing so an entire genre of music has disappeared from my phone. They are larger mp3 files, about 45 minutes each, that i created myself. Itunes reports the music as being on my phone and the storage space is being used by it. The genre appears in the library, but is empty. When searching for the song names nothing shows up. I even went as far as to delete all the music off my iphone and then reload it with itunes. Same issue. I have 2 genres that work, but this one does not. I feel like this must be a bug in iOS18.1 because i've tried everything else. Any suggestions?