When I load into a game, the terrain is black except for when different types of terrain are in contact with each other. Essentially it's all black with outlines of the different terrain zones (grass, water, mountain, etc). All the buildings are fine. If I hover my mouse over any of the menu buttons at the bottom the terrain comes back. If my mouse is hovering over anything that presents a tool tip, the terrain also comes back. Once my mouse leaves those areas the terrain goes back to being black.
Radeon R9 290X