Past 18w01a my world will not load properly. Upon loading it will crash. All previous versions and snapshots it will work. Testing has shown that if forcing it to load into the snapshots that crash the world repeatedly, I can then load back into one of the versions that load properly and it slowly resets all the chunks back to default erasing all world progress. Further testing has shown, if I leave myself in the end in working versions, I can then load the world fine in 18w01a and beyond, just to move around seemingly fine in the end, but trying to transfer to the overworld, after so many blocks, the world will crash again and become bricked in newer updates requiring backups to be reloaded and testing to start over.