I am also having the same problem and I don't want my name to get sniped when it becomes available. I should be able to switch it back but it says its already taken! this is not good. I have 6 days now and I'm hoping Mojang support gets back to me before its too late. I didn't start getting this error until I migrated my account. now I cant switch back.
Thank you so much ined! I thought i was gunna lose my favorite username! 😃