Thank you for such a fast response!
The problem seems to persists in both single missions and war patrol. If I use the "quit" option in a single mission there does not seem to be a problem, only when I manage to sink something and then "win" the patrol. In war patrol I get the problem already when I select save & exit right after starting the patrol.
When I play the lite version I seem to never get this problem.
I'm still not sure how I manage to fix the problem as it seems I have to clear cache, start game, clear cache again and start again and so on until finally the game gets past the loading screen. Force quitting the game does not seem to fix the problem.
I have a strong feeling that the problem might be related to internet connection. Perhaps the game is trying to connect to internet to update the high score?
I sent my device ID by e-mail to you. Hopefully this information helps!