App freezing after converting from old world to infinite

I switched one of my existing "worlds" that was in creative mode in the "old world" type to "infinite". Each time I open up this newly created infinite world moments after I begin to move around in it the game freezes. I am playing PE on my iPhone 6s which has the latest software update installed. I have restarted the device, closed the game out and restarted it and each attempt has been unsuccessful in avoiding this "freezing" of the game.

Thanks,
Michelle