Warning!
If you’ve patched your TS4 game make sure to do backups of your saves before playing! It seems that the “improved” save feature is completely borked. Whatever you do, don’t press “save” since the game might automatically overwrite another save game than the one you’re currently playing. Reports have also come in that the game might refuse to save your game if you use a custom name for your save. Beware of this too!
If you’ve experienced anything of the above please consider following this link:
http://answers.ea.com/t5/The-Sims-4-Bug-Reports/Save-Issues-after-Update/td-p/6081467
and press the “Me too” button on the first post.
Careful Simming!