lighting changing depending on object rotation - noobie question I'm sure


I’ll make this short and sweet as I am sure it is something someone will be able to explain fairly quickly, why does the above occur?

Every mesh is the same mesh, just rotated. Each rotation seems to somehow modify how the top of the cube receives lighting, and I have no idea why.
The bottom left beveled cube is the original with no rotation.

What am I doing wrong here? A freshly made, non-rotated cube for the corners yield the same weird lighting result, and it also persists once the meshes are turned into an instanced static mesh.

Can provide more details if needed, just ask away!