By first glance I had thought it could just be the person's device version or whatnot. But I continue to see that the people that report the problem have loads of dwellers ( About 100+ ) and lots of buildings. So I think it could be the RAM ( Or Memory ) that the game requires and continues to use it. Although this is just an idea, it COULD be the reason why. Anyone else have any thoughts? Btw since this is happening to people with loads of things in their vaults, I kind of get frightened if I continue to progress my vault, it will crash and I won't be able to play it anymore.