Nope, that didn't work for me either.
But I can say this: All my music was in the cloud. ie, I had the cloud icon beside all the albums I was trying to "get album artwork" on (I use iTunes Match).
Every time I clicked "get album artwork", iTunes - bless it's arrogant soul - responded with nothing. Nothing happened. No message. No status.
So I tried this: I first downloaded just 1 track from the album in question, from the cloud (no need to download them all, I prefer to keep my music in the cloud).
Then I followed danno2022's suggestion of right-clicking that track (not the whole album) and selecting "Get album artwork". And voila! iTunes artwork retrieval function sputtered to life, and it downloaded the artwork for the entire album!
Another tip: always make sure your album is named exactly the same as the one for sale in the iTunes Store (and that it is actually available in the iTunes Store you are using - every country practically has a different store, and the content varies between them) - otherwise iTunes will never retrieve the artwork.
(Most of you probably know that already, it's pretty much iTunes Madness 101.)
cheers,
C