After finishing the SP campaign I went back to MP and suddenly the grass textures on Lighthouse aren't black anymore
I'm guessing it gets fixed after you play the Island mission, the one where you have to get to the Prism building.
Try and see if it works

It usually works on the FIRST map loaded in rotation, then after its glitched. If lighthouse was the first map you loaded while online, then ya it will work once.

ALso exiting to single player, then going back into multi fixes it for ONE map, then afterwards its glitched again..

It's dark again
lol