I had the same problem and spent hours trying to figure it out! My problem was actually on the HTC One X but I suspect it's the same issue.
At first I thought it was probably an issue with some files cached somewhere because I'd moved a few things around and deleted and renamed some files, but after noticing I had the same problem with players other than the stock player, that pretty much ruled that out, but I still just couldn't figure out why no matter what I did, two of my 300ish albums were showing without artwork.
Eventually I figured out it was because Android didn't like something in my ID3v2 tags. Because most of my music is in OGG format this generally isn't a problem, but I've still got a handful of MP3 albums, two of which had this problem. The tracks in one of these albums had 'Encoded by iTunes' in the 'Encoded' field of the ID3v2 tag; removing this from the fields resolved the issue and brought back my artwork. I couldn't figure out what was wrong with the tags in the tracks in the other album, but removing the ID3v2 tags then adding them back in fixed the issue for that album too!
So I've still not got a clue why this causes a problem, because the ID3v2 tags weren't incorrect, but Android wasn't happy with them for some reason, even though the tracks still played fine.
I hope this helps someone else anyway - I'd be interested to know if it fixes the problem for others too