Just playing around with the new app, delighted so far but I do keep managing to crash it, by clicking the icon which is 3 horizontal lines at the bottom of a scene/document, the one next to the bookmark icon. For a second the screen says 'Loading Draft Preview' but then the whole thing crashes.
Any changes I made pre-crash are still there, which is wonderful, but I still don't even know what that icon is supposed to do

It happens in every scene.
I'm using an ipad mini, ios 9.3.3