Music app showing artists in wrong sort order
I'm running iOS 8.2 on an iPhone 6 128GB.
In the Music app, I've noticed that some of my artists are listed under their first name when I specified their last name within my iTunes library.
I have populated both Artist and Album artist sort fields and it seems to be happening at random.
For example, I have a song by Paul Simon to which I have applied the sort "Simon, Paul" and this appears under 'S', as you'd expect. However, another track by Carly Simon (and sorted as "Simon, Carly") appears under 'C'.
Within iOS, I have my music set to 'Group by Album Artist'. I've tried removing the affected artists and re-syncing, changing the sort fields in iTunes and back again, even deleting all 4,000-plus songs and adding them back. Alas, the problem remains.
I don't particularly want to do an erase and reset to factory settings. Any thoughts?
iPhone 6, iOS 8