When I updated my whole computer, I opened Minecraft and I went into my newest world, but for some reason, I thought these mountains were cut in half until I went over to my house which is on a mountain and found my roller coaster which is very long, cut in half. I flew upward and found that chunks of land in square forms have moved. I went back down and checked whether my horse is there and it was gone. So was my cat, bird, and cow.