I encountered this bug as well on Here comes the flood.
I tried to restart my iPad, close out the app, and it still would make me roll for items again at the general store, background screen would go black, and it would not let me progress.
I also forfeited the game, it gave me the victory screen, but then when I went make to the main screen, it said that I did not complete the scenario. Definitely a big bug.
I have an iPad Air 2 with iOS 9.3.2 (latest update).