I haven't found a post with my issue. I play without wifi or multiplayer. It's an infinite flat world and the ground suddenly disappeared. It's just blue and all the blocks in it are invisible as well. I've tried getting off and getting back on, but it's still there. As you can see, I'm building a rollercoaster so there are a lot of fences around. I thought maybe it was just an overload issue? Everything else is perfectly fine.