See pic. This only shows up on this one map in this one saved game and I checked several. It even shows up when I tried a map replacement mod. No mods at all and still there. Thoughts?

Game repair?

Tried that but its still there. So weird. Because its confined to the one save I've decided to copy the main houses and families I play, delete that save, and hope that's the end of it.

So a follow up...I found the lot that was causing it, but I still don't know why. I literally tried removing everything on the lot in chunks until it was totally barren and no change until I actually bulldozed the whole thing. I have no idea what it might have been but apparently it was invisible. It was not a lot I built or actively play, so I dropped a different house from my library and no issues so who knows what was going on there.

That's very weird. glad you could fix it!