iPod Album covers not showing up

When I use Home Share with my ATV's, iPhone or iPad, I get very few of my album covers to show up. They are visible in iTunes, but 99% of them don't show up on the other devices. I asked the Genius Bar yesterday, as I was at an Apple store for a different issue, and the guy I talked to said he had the same problem. He talked to someone else who suggested to turn off Home Share on iTunes, then turning it back on and then also resetting the ATV. I did both and the problems still exist. I should also note that all my movie artwork, which I have converted from BD or DVD via Handbrake DO show up just fine on all devices. So, the problem is only on the music side. Anyone have any ideas? Thanks in advance!