What is causing these texture/shadow artifacts?

Hi all,

can anyone point me in the right direction here? I’m trying to find out what causes these artifacts (pictured).

As the top face of my mesh approaches the landscape (along the Z plane) I get diagonal lines. These lines move with the mesh when shifted along X or Y axes (even with a world aligned texture) and fade away as I move the mesh up on the Z axis. I have the same result on Static Meshes that I create and unwrap in Blender as I do on BSP Geometry converted to a Static Mesh in UE4. It does not occur on BSP Geometry - only when I convert it to a static mesh.

Changing my post process volume settings and rebuilding lighting removed these artifacts.

I noticed later on that they were only present inside the post process volume so drew the conclusion that they were linked to lighting simply needing a re-build.