Unloaded world disappeared

After updating the new 1.2.14.3 update for iPhone, I went into my world I set the render distance on 32 chunks and flew around. Until I came to the “edges” of where I’ve created stuff, the unloaded world I’ve never been to. Now the world is like a floating island in the air. But when you want to “jump off” the world, you can’t. First you are falling like 40 blocks down until you hit the “bottom” of air, which is locating on -40. Can someone tell me what’s happened or how I could fix this, because I can’t expand my world anymore, surrounded by “edges”