See licensee video here for an overview - [Link Removed]
Download the licensee repro from here - [Link Removed]
When using PIE, the self shadowing changes (gets darker) as you get closer to the ladder mesh in front of the camera.
If you use ShowFlag.VisualizeGlobalDistanceField 1, and approach the ladder again, every 5000 units, the scene appears to "jump" the camera back to the origin, which does not match up with the regular lit scene. The video illustrates this best.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-177864 in the post.