@Nabril I tried what you suggested with changing the front door designation to the gate, then back again. No change there.
@Nikkei_Simmer I'm assuming you're referring to the empty lot being corrupted, correct? I wonder if it might have anything to do with the fact that before I could place the house there, several sim weeks into the game, I had to build a small structure and bulldoze the lot. Apparently, it was the spawning place for some of the NPC's, and had the vacant house lot tag, instead of the empty lot tag.
