Volumetric Fog in lights getting odd artifacts

Hello!

I get odd artifacts in my volumetric fog coming out of my spotlights. They are inside a blueprint. There are “spots” where the volume isn’t visible. See screenshot (never mind the different colors of the lights):

I’ve tried increasing the grid pixel size and other console commands, nothing has changed what’s happening so far. Removing all lighting-related actors (height fog, lights, atmo, pp volume etc) and rebuilding them from scratch does not remove the problem. Any suggestions appreciated if you’ve seen this error before! I haven’t.

EDIT: These “splotch” artifacts also appear further out in the light fog, not just at the “start”. Almost like there was a soft noise being applied at world scale or something.

This is in UE 5.5.1.

Not what I wished for, but downgrading to DirectX 11 fixed it for now.