I updated to 1.11.1 and the game crashes when I load or create a world with the Zig Zag texture pack. It seems to be the only texture pack affected.
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However, this issue has been closed as a Duplicate of MCPE-40666.
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After another hour of playing with this, I found the issue is with the 128px option and the 64px version works. All other 128px texture packs work on three other iPads, just the 128px of the Zig Zag texture pack does not work in MCBE 1.11.1.