Try resetting your user files as described in the factory reset described in this post: http://answers.ea.com/t5/The-Sims-4/FAQ-Troubleshooting-Steps-amp-Known-Issues/m-p/3621199
You won't loose anything. Just make sure to not delete any files and make a backup.
I was having the same problems with my sims houses or renovations I did disappearing, I have played for awhile with no issue, but after finding the factory reset post, not to mention going ahead and using the origin repair mod it completely fixed my issues!!! thanks so much, p.s completely uninstalling the game and reinstalling it did nothing for this weird bug!
Did you start a new game after the reset or was it your bugged save that started working again
