UE5 Lumen: Flickering and total darkness in dim room

[AGiraffeAndAHalf]

video demonstration: Unreal Engine 5 - Lumen Issues: Flickering & Darkness - YouTube

Simple premise, open the 3rd-person starter, make a room with some narrow openings for light to create a dim atmosphere.

With the setup in the video, the whole room is fine except that one corner which flickers and then goes dark when approached.

Changing the setup so there is less light in the room causes this to happen more easily.

I’ve modified every setting I can find regarding lumen, distance fields, both hardware and software modes, etc, all display this behaviour.

I also tried double-sided distance fields as another poster said worked for them but it caused insane and somewhat hallucinogenic color bleed from the lights on the other side of the wall so that’s a no-go.

[IceDDZ]

What’s your Show>Visualize>Lumen Scene view of that part of the room look like? Are there leaks with the distance field meshes? Also are there any emissive material meshes around? Even on the outside of the room, nowhere near it? I’ve had issues with emissive materials on meshes REALLY messing with the smooth lighting that Lumen CAN provide. I’ve had plenty of random unsolvable bugs with it so far.

[AGiraffeAndAHalf]

pics of LumenScene, LumenGlobalIllumination, and mesh_distance_field attached

unfortunately I have no idea what I’m looking for in the LumenScence viz.

There was one emmissive mesh in the level but moving or deleting it doesn’t change anything.