iTunes 11 Match. Missing Artwork mystery

Hi All

Been playing around with the random missing artwork thing with itunes match as i feel there never really has been a decent explanation for it. Using Win 7 64-bit PC. iTunes 11.

Give this a go.

Create a smart playlist to match the following rule.

Has artwork - is False.

This will create a smart playlist containing all the files iTunes beleives to have no artwork. What I found was quite interesting. The resulting playlist contained many tracks that clearly do have album art, as you can see the album art. and also contained all the tracks the definately don't. So it seems even itunes really can't tell when a file has artwork or not.

Also just some further detail. The library I am currently looking at is on my work PC. Its a "fresh" library using itunes match so none of the files are actually stored locally. What I am looking at is entirely what my iCloud perceives my music library to be (and matches up with what im seeing when I look at my library using itunes match on my ipad). So some of the album artwork that is missing I know actually should have artwork as there are particular files I know definately has the artwork my home PC.

Does anybody know if icloud will push any changes you make to the icloud library down to files stored locally in an itunes library?

anyone else seeing / experiencing similar issues?