I'm having the same issue. Were you able to fix it by inserting the SD than resetting the phone?
Sorry for the long delay. Just did some more troubleshooting and no that didn't fix it.
I now have a new issue with the DRM Xbox music tracks involving the "In Collection" and "Xbox Music Store" connection between an artist no longer exist. So, removing and formatting the card did not fix the problem. In fact, I have the issue when the SD card is removed from the phone. In fact, there is not even any music, videos, or podcasts on the phone's internal memory.
Man, I have had this problem with both a Lumia 820 and Lumia 521. I have been a windows phone ****** since WinMo/PocketPC days, but the constant bugs I keep getting with WP8 are making me think I should switch to Android. The main things I use my phone for are calendar, email, and music/radio...2 out of 3 of those I have had constant issues with. I have used a Samsung Focus, Focus S, and Lumia 900 and I think that all three were way more stable then the two WP8 devices I have been using.