My scene has a box 45 m × 45 m × 10 m in height. The bottom face is located at Z=0. In the viewport render the bottom face renders black, when it should render white like the other faces.
If I move the box 2 mm upwards, the bottom face now renders white.
If I move the box 2mm down again to the starting position, and move the box origin to Z=0, the bottom face now also renders white.
Can someone explain why it renders black in the first position, and why changing the position or position of the origin affects the render?