@softestbreadloaf Maybe you got lucky and ran into multiple issues at the same time. In particular, does the lot that won't load have the Off the Grid challenge? If so, please remove it, which you can do in Build mode. Choose Load Game and load to the Manage Worlds screen, then click the lot and choose to enter Build/Buy.
Please also go into Documents > Electronic Arts > The Sims 4 and delete any lastexception files you see. Try to load the lot again, after removing OtG if it has that challenge, and if the game creates a new LE, please provide it here. You can copy and paste it into a reply (please use a spoiler tag), or create a .rar file, or delete the first line of the LE and attach it as a .txt file.