last turn has to be completed by both sides simultaneously. south first until the last one, then both together.
if you reset phase and cant click them or don't have any option to reset phase in the first place, you have to wait for a soft reset before you can proceed. It's happened to us several times, and we've always just picked it up the next day. A soft reset could take 30 mins, or 3 hours - no way to know.