Just to do a more 'public' update in regards to this bug, as we've been getting a rash of reports of this lately:
It's on my radar to fix as it seems to be effecting a large portion of players. Haven't nailed down the exact cause yet, but it appears to stem from users having emojis in their gamecenter names and being the first game in that person's 'turn list'. Not 100% sure on that yet though. It's obviously taking me a bit longer to get around to it due to SFT being in early access as that is our #1 priority at the moment.