I also never knew that about the Residential rentals! It's strange because the first time I put it down, everything worked fine (I could delete and place items) but then the loading screen wouldn't stop. I Forced Quit and when I went back into the game, that's when I started having Build Mode issues.
@SkyhunterXoX Might be worth doing a fresh folder (Exit Sims 4 then drag your whole Sims 4 folder from Document > Electronic Arts to your desktop. Launch Sims 4 and reset your Options. Add old content into the new folders after the game seems to be behaving), and even a Game Repair. Also, there's definitely most-recent-version mods out there that are not compatible with the current version of the game or with the new pack.
Thank you! Turns out one of my mods was outdated, specifically Control Any Sim by TitanNano. Thanks for all your help!
