Cannot assign rooms in small business

I've registered a residential lot as a Small Business in The Sims 4 Businesses and Hobbies, and every room is automatically set up as Public. I can't change anything to "Residential" or "Employees Only," because the option to do so is greyed out. I kind of get around it with locked doors or gates, but even then, ghost customers phase through the doors and steal from my fridges, and customers gather at my sim's residential door en masse trying to use their home utilities, like trying to get food from their fridge or watch their TV, all while not buying anything.
To save some time: I've completely removed my mods folder, I have repaired the game/verified files via Steam, I have deleted cache files, everything that is normally suggested. I'm really hoping that I'm just making a dumb, easy mistake like clicking one button I missed.