Issue when editing the perspective matrix

I got this artefact in UE 4.10. In version 4.7 works.

artefact.jpg

Does someone know the cause?

What’s a perspective matrix?

I think this is due to temporal aa/motion blur. I remember trying this out about a year ago. I’m surprised it still works on a current build - this was with the source code alteration yes? I’ve been looking to give this another look.