As you can see here - when using album cover view, some of the albums show blank covers. However if you click on the album, you can see that it actually DOES have album art.
This is happening all over my library and I'm not sure how to fix it.
Editing to add: if I right click, select edit, and then just click save without making any changes it seems to make the picture show up. But it would be nice if I didn't have to do this for every single album.