Minecraft PE cut world bug

Okay, so on a survival world in Minecraft PE, my sister can't come near my house because on her kindle it looks as if my house doesn't exist. It was cut off by the glitch. I had built my house near the edge of the world, and when she updated her Minecraft to play with me, my house was cut off. It wasn't cut off to me, but it was to my sister. Actually, when I go to my house, when my sister looks at her kindle, my character is appearing to stand outside of the world barrier. I did download an inventory editor app that would get me diamonds, but once again, the bug is on my sister's kindle, so that can't be the case. Anyways, in the next update, please fix this! By the way, this affects the version v0.9.0 alpha, not 1.7.10 on PC.