IPhone 5s :: IOS 7.1.2 / Album Artwork Disappeared In Between Tracks

I was listening to one of my playlists on my 5s and was looking at the album cover on the "Now Playing" screen. Playlist was on shuffle, and when the next track came on, no artwork. I hit the back button to see the playlist, and every song had converted to a black box with with the album artist and title printed diagonally.

I had not added anything, or synced to iTunes during this time. I did, however, purchase one track from iTunes directly to my phone earlier in the day. Interestingly, that most recent track is the only one that still has artwork. I have a 32gb, with 3.5gb available, if that matters. I turned the phone off and on, then hooked up to my computer's iTunes, highlighted all albums and clicked "get album artwork," watched as the ticker at the top of the screen scrolled through the numbers of albums being updated. Once finished, synced iPhone to the computer. Â

What caused every piece of artwork and genre icon pics to be removed in the course of a playlist shuffling from one track to the next?Â

Info:
iPhone 5s, iOS 7.1.2, 32gb