in my UE 5.6 Archviz interior scene with Lumen and Raytracing I unfortunately get this flickering effect (see video). The funny thing is, it only appears on that particular window (same mesh like elsewhere). When I get closer it disappears. I already tried a lot of settings including TSR and cranking up lumen scene detail without luck. Only adding a quite big contact shadow in the sun settings helped but it looked awful.
Can someone please help me? Would be much appreciated.
Checking around the community, when Lumen and Ray Tracing are combined, they do have a tendency to create conflicts from time to time. And since the problem is affecting only a few meshes, it’s mostly related to an element within the project. Just in case, let’s ensure your setup is in order:
First of all, please update your nVIDIA drivers, make sure you are picking the “Clean Installation” option, as well as going for the “Developer” drivers, as these have more stable settings for engine work.
Next, if your current project was recently migrated to 5.6, rendering settings from the previous build could be causing issues. In order to reset them, please search for the “DefaultGame.ini” file in your directory, open it with a notepad, and delete all settings under the header [/Script/Engine.RendererSettings].
Now, to confirm if this a mesh issue, simply swap the window mesh for a different one, or create a test cube in your level, using the same material. You can also take any problematic meshes to Blender, and do a normals pass, check for any non-manifold geo, and add a bit of thickness to any single planes.
Then, if the cube test is also flickering, then we need to check the engine’s config. Try enabling “Ray Traced Translucency” in Project Settings, and setting the material’s “Refraction Method” to “Ray Traced”.
If the issue persist, please check the related threads below, there are further methods to try for your scenario:
