Album Artwork Not Syncing With iTunes Match

Hello All,

I am having a problem with the artwork on my albums. When I change them all to how I like and then 'Update iTunes Match' they all go back to what they was like before. I'm the kind of person that likes things organised so when things like this happens I go mental.

Everything else with iTuens Match I love. When I change the name of the song I watch my other iOS devices and see it change on them too. When I create a new playlist it creates a new one on all my other iOS devices too. But the artwork is the only thing that resets itself.

Can anyone help before i delete the who of my libary out of anger.

P.S. Can someone just confirm what 'Update iTunes Match' does.

Many Thanks