I commented before, but I wanted to add more information. I had multiple saves that were just fine and then the problem started again. Not only are saves inconsistent, but I've had some things save and others not. I built a new house and saved and exited to the neighborhood, and then exited the game to make sure it stuck. It stuck. I added a family and began to decorate. When I was done, I exited to the neighborhood. The house was gone. The family was still on the lot. I went in to see if it was playable. It was. The family was fine, but they were alone on a vacant lot despite the house having been built first.