World shift

When I loaded one of my old worlds I hadn't been on for a while, the world had shifted. It is and old finite world and the barrier marking the edge of the world had shifted, cutting off a chunk of the world from one side and adding a proportionate chunk on to the opposite side. This happened after I did the new update, but I haven't been on this world in a while so it might be from before. I don't want to check my other older worlds as I don't want the same thing to happen to them. The photos aren't super clear, but part of my world was just deleted. I didn't toggle any of the experimental switches prior to this.