Im not sure which version but after todays update (the shields and crossbows update) i entered my og world, and walked over to my iron farm. There is a huge chunk missing from the area that used to be here. Originally the area was never mined and had a forest. I threw a carrot from my farm to my left and the carrot just fell through im assuming this is an open chunk to the void. This is probably not a glitch, as my map shows that these holes are black., like a map in the End would, and mobs avoid the edges of these chunk gaps..