Thanks for the advice..i have an iTunes Match subscription and it still reverts back to the original artwork unfortunately
A couple of bits? Are you working on a proxy of your iTunes library? I find this only works by making changes to items while using iTunes "talking" to my iTM account - easily done by me on another Mac or even a second user account on my main Mac (Standard Account, logged in to the iTS while not linked to the Library you're trying to make changes to so that you're connected to the cloud music and not your local music). When I make a change to my iTM items, I've found that, after several seconds (5-10), there's a bit of a "flash" or redraw on my Mac's screen in the Artwork - I leave my Get Info dialog open until I see that redraw; I'll often, but not always have my ATV on with the Music app open - after that redraw it's as if it's been uploaded to Apple's servers, and a few seconds later I'll see my change showing up on my ATV (or iPhone or iPad). Eventually, I'll get back to my main music Library and the changes sync down.
I was working on getting artwork for Freaky Chakra's Lowdown Motivator (don't ask, love the beats...) while at a field office - and it was driving my crazy at the time, and then the phone rang. When I put down my iPhone, there was the artwork, in its Music app.
So, work on a proxy and not your main Library, make a change (it works for lyrics too...), and wait for several seconds.
That's all I've got...