So about a month ago I upgraded my old world I created back in 1.14 to the 1.18 snapshot and it seemed that everything ran fine but just recently I discovered that my old chunks were not generating the new 1.18 caves beneath them like they were supposed to. When I mine down to y=0 the bedrock is still there and nothing has changed. So I thought I just needed to go load new chunks, no big deal right? Nope, apparently when I go load new chunks with the new caves and then I go back to my original chunks it will lag out and crash my game and I have to restart the game and start over again and if I try to load my original chunks again it will just keep crashing. The only way the game will not crash by returning to my original chunks is if I travel there by nether or I respawn at my bed in the original chunks. I would like to know why my world did not convert to 1.18 properly I even used the feature to optimize my world to 1.18 and unfortunately nothing has changed. Can I please get a solution to this because this is really freaking me out I don't want to have to start a new world because of this glitch I really hope there is a fix for this.