Province 12-9. Just finished a battle and it locked hard on the Victory screen. Had to force close the app. Nothing else locked up on my iPhone 8. Lost the energy used to play that battle, and didn’t get any rewards since it didn’t get to that screen. It is on iOS 11.2.1.
Not sure what caused the error (this might happen when your internet service is temporarily disrupted).
You can contact Game Support from ingame (main screen), by clicking:
Menu > Options > Support (other issues)
usually get a disconnected from server error when that happens. If it happens again, I pursue it with support.