@Freddy_Falkner Thank you for the advice, it could be storage space on tablet. I've played for a couple of years without any problems and it just seemed strange it happened out of the blue.
Thanks @Tzvi_Marcu I've been playing on my tablet forever and it's never happened before always in the same way. My tablet could be low on storage..... not sure this would be a cause. Do higher levels cause issues perhaps? I'm just below level 3900