Large models like mountains not casting shadow on plane

I have created a simple model for mountains in blender that I intend to use in my game. My intention currently is to have mountains in front of a sunset, so big shadows are present over a plane, but the mountains aren't casting any shadows. I have angled the light so that shadows should be casting onto the plane, but they aren't. I also have a tiny pedestal that does not display any shadows onto the plane either, but I do have a tiny sign on top of the pedestal that is casting a shadow onto the pedestal. I have checked that every object has cast and receive shadows enabled. So why aren't the mountains casting any shadows?