Foreground sprites inappropriately light up background geometry when Lumen Screen Trace is turned on

Hi all. Anybody know a workaround for this problem? Turning off Lumen screen tracing fixes this issue, but introduces an unacceptable amount of light leaking.

I have a dark scene, and a 1st person character holding a torch:

If I move the camera so the torch is between it and and dark background, the background geometry is inappropriately lighted by the torch texture:

This wouldn’t be so bad, but the effect persists after the torch has moved:

Here’s a video of the issue:

The torch is a particle system and its material is lit translucent. It’s outputting to the emissive channel, but I’ve turned off all the light channels, and emissive setting I can find with no luck. Even turning off the “Show in ray tracing” settings on the particle’s component doesn’t solve the problem.

I feel like there must be a way to keep these sprites from contributing in any way, but nothing I’ve tried (except turning off Screen Traces) has made any difference.

I can’t turn off screen traces because I get unacceptable light leakage at the edges of objects.

Anybody experienced this and have a workaround?