Actually the thumbnail pictures stopped being updated every time you saved the file considerably earlier than 2013. I'm running 2010 and my thumbnails update in some manner that I have never been able to figure out. I have no answer to your problem, just wanted to clear up that point, since it ticked me off when they changed the way it worked.
Thanks for your reply Jerry.
I contacted support about this and they have verified the issue and created SPR 803351.