Any covers that display a musical note on a gray background are missing art.
If you prefer the traditional list view, pick "Songs" from the View drop-down menu, and then check "Show Artwork" and "Always Show" to display cover art.
When i Tunes syncing works as intended, that’s fantastic, but sometimes things don’t work out that way.
i Tunes 12 in particular appears to have some annoying issues with syncing that causes a sync and media transfer to get stuck on a step and never complete, sometimes just filling up your device with music and song names that can’t actually play.
If no art appears on an album, the i Tunes Store does not offer the album you chose.
To fill in the gaps that i Tunes can't download, you'll need to find and save the artwork from elsewhere.
To obtain the covers, use i Tunes on your computer to find all the albums with missing art, and then either download the art from Apple or import it from an image file.On occasion, i Tunes 12 stops displaying art for albums that already have art downloaded.If you open the Info page for a song and see the cover displayed at the top of the page, click "OK" and the art should work correctly.If you have a physical copy of the album and a scanner, scan its cover for a high-quality image.Otherwise, search for the album by name on an image search engine or a Web store that sells CDs.