I am having this same problem.
Player: #7149
iOS: 10.2.1
Model: iPad Mini 2
I click on Story Mode, try to select a party (or create a new one, doesn't matter), the screen freezes for a couple seconds and then the app crashes.
Quest Mode works fine.
Doesn't seem (at least to me) to be a space issue, I have plenty of space available on my tablet. I've tried with effects both on and off, I've tried logged in or not, still crashes.