Artwork shows up correct in iTunes library but wrong on iPhone 6s.

When I add music to my iTunes library on my computer the artwork shows up perfectly correct, but when I sync my phone after the artwork is a duplicate of another album. The only way I found to correct this is by Erasing All Content and Settings and then restoring my phone. Before iTunes 12.1 (or whatever the newest one is) I never had to do this, so does anyone have any advice or do I have to keep doing this tidious manuever whenever I would like to add music to my phone?