Can't speak for the OP, but in my case, I had it happen twice between beta 1 and beta 3 when I tried to skip beta 2 because I didn't care that much. It was also an iPad that left upstairs and was too lazy to carry it downstairs to update. Not a primary device, so all I lost was some progress in a few games, but I can see how someone could have suffered the same fate with their main phone and have lost a lot more.