The problem was a video with a bad thumbnail (or metadata) that either Apple or the music company's broke by screwing around with albums. The original album was removed and replaced with a identical copy on Apple's content servers. In the process they broke one of the old tracks, a video.
Broken album info:
Item: Prospekt's March (Bonus Video Version)
ID:
id296910095
And what it was replaced with:
Item: Prospekt's March (Bonus Video Version)
ID:
id385861818
The fix was to open OS X iTunes, go into "Purchased", make sure it is set on list view (Album view would throw up the Error*), and then hide that single video. If anyone has purchased Prospekt's March by Coldplay and can't get that artist to load in "Purchased", you now have a possible fix.
*Error: "failureType5002 customerMessageAn unknown error has occurred"
Now to figure out why iTunes Plus tracks are showing as DRM'd if downloaded in iOS 6 (can't load them into GarageBand, iMovie or any of the ringtone apps).