Before you turn to a factory reset, since you are balking at the idea, it seems there are still alot of variables you could consider.
Have you uninstalled or disabled ANY stock software that comes on the phone? Sometimes applications have been tied together, and inhibiting one that seems unrelated can have negative results on other applications. For example 'Car' or 'Soundhound' or 'Tune In' all have ties into the music application and eachother. There could be other programs with ties in that are much less obvious than music related.
If you have any kind of task manager/power managers installed it could be halting the audio enhancer without your knowledge.
In your photo Power Saver was on, maybe it halted the Music Enhancer to conserve CPU cycles?
Music also has a settings for automatically updating Album art, Artist Photos, and Lyrics. If the phone is trying to update these in the background and it cannot connect or is running into issues I could easily see it crashing