Download the licensee repro (space scene) from here - [Link Removed]
The issue is immediately visible when the scene opens (licensee has also provided images in the UDN which highlight the problem). Black artefacts around tiny stars in the distant texture.
The easiest way to see the issue by comparison in editor is to switch between FXAA and TAA in editor. There are no artefacts with TAA.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-135727 in the post.