I came across this bug when playing in the Nether for the first time I saved in the lava because I wanted to load a new world and I started up the world again and found myself at the top of the nether on the flat land of bedrock it it works as long as the player can interact with the blocks that it's in the player possition does not save correctly and you get to the top of the world aka it places you there by trying to find the first solid block from the top of the world downwards. no screenshots because I don't know how to show this bug as you can fake it by going in creative and destroying the layer of bedrock at the top.