DISCLAIMER: All views are considered my own and you should not draw any conclusions on associates.
Technology sometimes... Let me imagine your scenario, you are organized and have your music library is a bunch of folders. There is no audio file in sight as you scroll down. This is probably where the music app is getting confused. Solution: you need one music file insider of the root view of the music library then it will scan the rest of the directory hierarchy and find all of your other music.