"shimmer" side effect with motion blur enabled

Hi all,
I have a scene that I’m trying to do a sort of “tron style” motif - so lots of plain emissive lines and such.
I’ve added a post process volume that has motion blur enabled.

I’m finding my player controlled ship is emitting a very weird sort of “shimmering halo” around it with motion blur enabled.

It’s an infinite racer so the track is moving but the player ship is actually stationary (save for moving left and right).

What I’m wondering is: what can I do to prevent this effect from happening while still keeping motion blur enabled?

I have tried all sorts of tricks with custom depth and everything has basically failed. If there was a way to have this actor simply be ignored by the velocity map UE4 generates that would be cool, but I don’t think something accessible unless I wanted to do engine level modifications.

I have also tired disabling AA and the result is even worse.

As an aside, does anyone have an explanation to why this is happening?

Anyways, ! I hope one day we’ll be able to have objects/materials be ignored by motion blur!

As this is way more evident with motion I’ve uploaded a gif demoing the issue to gfycat below

a bunch!