Music library split into two within music apps?

[AC Question]

Hi, I recently updated to android marshmallow on my HTC One M9 and since then, music files on my phone have loaded into music app libraries weird. At first, they would only be at the very top of the Alphabetical artist list no matter the name of the band. Now, my whole library is split in two. I open my music app, everything looks fine, but there's a ton of music missing. Well if I scroll down to the very end of where my music would be, artists starting at Y, it just continues at A again and has all my missing music in another list at the end.