I had the same issue. I think it involved unmounting the SD card.
We called T-Mobile tech support line and they walked us through it. We were able to go through the steps on one phone while talking on the other (you may want to take notes.) After getting off the phone we were able to quickly duplicate the process on the 2nd phone. That was a few weeks ago and now I can't remember the steps (wish I'd taken notes.)
J.D. Power and Associates awarded T-Mobile customer service the #1 ranking for good reason. Let them prove it to you. Give em a call.
Thanks! I finally got around to calling today and they weren't able to resolve the issue, so they're sending a replacement. Hopefully, this will resolve it! If you happen to remember any of the steps I'd love to give them a try. I actually did unamount the memory card and still no luck.