Distorted Swimming Pool Walls

As of maybe two days ago, whenever I create a swimming pool and go to save it, the walls of the pool appear distorted/transparent. The first time I noticed it was right after I created a natural swimming pool and went to save it. I attempted to place the saved pool on another lot, and all the objects I added to the sides of the pool were floating in the air.

I tried everything I can think of to make the problem go away, but each time I create a new pool and go to save it to my library, you can still see the problem with the walls.

I don't use any mods or custom content in my game, and I own every expansion, game pack, and stuff pack.

Please help. ☹️