Problem with Spot Lights on Terrain

I'm doing small projects messing around with lights and learning how to use each kind of light effectively. I have an imported model I'm using as the terrain for my character to walk on. Then I set up a few spotlights to shine on certain parts of the terrain. However, I don't see any lights.

I thought the spot lights weren't working at all, but then I noticed that when the spotlight's shining on my player character, the light works. But only on the character. The terrain right below the player has no light on it, as if it's some bizarre effect going on. Even when I increase the spot angle/range settings (to make the light wider), it changes nothing. Only the player receives the light, but the terrain model does not.

I also tried the other types of Unity lights like the point, etc. but it led to the same problem. Oddly enough, when I use directional light, it "works" in the sense that it provides white-colored light to light up the whole scene. But if I change the color to anything but white, only my character changes in color, whereas the terrain stays lit in white light.

How do I fix this?