Things sometimes look dark (2017.3.1f1)

[sebas1111111]

Objects turn dark when they are at the opposite side of the light source.

Here's everything looking fine (the light source is pointing at the camera):

The building is lit perfectly, but the terrain in the background is darkened (the camera is turned 180 degrees):

If we get farther from the building, we see it turning black:

This is how everything should be lit. No dark areas or shadows.

[sebas1111111]

If we look at the building from the opposite side, and we go far away, it's not darkened:

[sebas1111111]

Here's a video in case my explanation is not clear.

https://youtu.be/Gt4CfFUXc2g