Chunk Relocation

I have closed and open this world many times before this point and today, I loaded in my worlds and saw that the cats I have just tamed, weren't at my home base so I explored the area and found a chunk of the ground disappeared. I switched to Creative mode to take screenshots and I noticed that my world had many chunks that disappeared or relocated.

What I expected to happen was...:

When I opened the world, everything would be ok and I could play like normal with my new cats and build my house.

What actually happened was...:

One section of my house was a pit with water at the bottom. The rest of the world had similar chunks that disappeared or were placed in random spots.

Steps to Reproduce:

I don't know why this happened. I've opened this world before and everything was fine. I will include screenshots. I can't include my save file through this, I apologize. The files don't stay within the folder.