Persistent crash on loading in iOS MCPE 1.11.1

If connected to internet, Minecraft crashes almost immediately (app gets closed automatically). If not connected to internet, loads but get 'global resources reset' message and then app freezes about 5 seconds later. Issue arose once I set app to login to Xbox, which I did for the first time today - prior to this I was using the app (in 1.11.1 and previous versions) without signing in to Xbox, without any problems.