I've been experiencing this issue quite a lot of times this recently.
Every time I either start a new game, move households to another lot, or even placing downloaded lots from the in-game community gallery. Most of the terrain textures are black.
I've tried repairing the game. But all files have been successfully verified. I'm not sure what's causing it. But its annoying as because I end up having to re-spray the textures all around the lot. Just to fix it. Which is the only workaround I can do. But tedious when I have to do it all of the time.