Ideas
I've been having this issue for a little while now. I assumed it would be mod related, as most issues are, but when I play the game vanilla, on a brand new save, the same thing happens.
For my test run, I took the gym in Ciudad Enamorada, into build mode. It already contains the Singles Hangout Lot Trait, that comes with the Lovestruck pack. Even with just that, I get the message that the save has timed out (Yeah, no kidding. I literally left the room, dried and styled my hair, before the message appeared, this time, because I could see it coming!
It makes no difference whether i Override, or Save New.
A 20 x 15 basegame house, with no lot traits will save just fine. Anything else; forget it!
I have already repaired the game twice. I have already run a clean uninstall/reinstall, twice. I even nixed my old save folder, in case it was corrupt. I'm at my wit's end.
Anybody else?