Problem with flickering shadows in Unreal Engine 5 when using global illumination not in Lumen mode

Tested and confirmed, but absolutely no idea. It seems it’s related to the reflection of the emissives.

Anyway, it seems like something interesting to be reported to Epic: Unreal Engine Community

What is Causing the Ugly shadow over the meshes on Reflection?

Post Process Setting

Translucency - Raster
Global Illumination - Lumen
Reflection - Lumen

Lumen GI

I have th same issue… and didn’t find anything to fix it for a while now. I feel that there is nothing I can do to stop flickering shadows…

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I have the same problem in different projects with different assets. I have flickering black shadows on grass and tree leaves when they are in the shadow. I have the problem in Screen Space GI, Lumen is ok. I have another grass asset and there is no problem to be in shadow. I’ll try to look at materials later.
If you want, you can view grass (right on the screenshot) in free asset https://www.unrealengine.com/marketplace/en-US/product/landscape-pro-auto-generated-material
asset is called SM_grass_bush01_lod00

Hi after the lull, good to see you again, I’ve been busy for a while and now I can get busy with Unreal Engine 5.

Bro as I see the problem you showed in the video has nothing to do with shadow flicker, this effect is more like z clipping 3d.

I noticed a change in the new version of Unreal Engine 5.4

It’s partially missing those flickering shadows. I opened the Photo Studio scene that is in the photo, and saw the flickering. But after I started the game by pressing play in the editor. I lost a huge part of the flickering. I mean, they’re practically gone! And after that they don’t appear in the project anymore until I restart it again.


Hi! After some time I started Unreal Engine 5.4 when it was released in full. And I noticed that the flickering problem becomes very inconsequential after I run the project.

You previously mentioned some reasons for the problems, please tell me where I can find this setting to test it with myself?

Check out my penultimate reply to this thread

hi i have the same problem i am gona list what i tried maybe it will help investigate the problem:
reinstall of drivers with ddu and without
clean reinstall of windows (only reinstalling main drive cleanly and keeping data from the other)
installing new versions 5.3 5.4
all projects have it even newly created
changing anti aliasing and testing with different screen precentage
changing material setting and testing without materials
changing cpu ram motherboard and gpu
tried every command i could find
disabling lumen
enabling ray tracing
to check what kind of flickering u can check on my post
thing that slightly hid the problem was enabling dlss but while moving u could still see it
also changing anti aliasing to faa and setting screen percentage to anything beyond 98 hid in editor but while playing flickering came back
i tried more but this is most common i have seen asked about