Re: No CC objects, but the game says it detected mods. Only this lot.
Things like paintings and photos that Sims made can end up counting as "modded". Also, even having mods installed - not just CC, including not just CC on the lot - can end up calling it "modded." The easy fix is to pull the Mods folder out, do your lot uploading, then put the folder back in. Just remember to not save the game. That will catch all causes except painting/photos and anything similar.
