Album Artwork Not Displaying Though it is There

I have this problem where some of my iTunes album artwork is not displaying in iTunes or on my iPad even though it is not missing from each track when I click on view info in iTunes. Most of these are with albums bought in iTunes such as the Complete U2.

Clicking on view info used to work to get the artwork to show up in iTunes but that no longer works.

Any ideas? Thanks

Deleting and then downloading again from iTunes Match seems to fix the problem. Must be a bug in iTunes. Others have complained of the same thing on the Apple forums.