Unreal Engine Issues
Unreal Engine Issues
Lumen reflections break when the normals don't match the pixel depth information.
UE - Graphics Features - Lumen - Oct 23, 2025Lumen Reflections can leave black spots in chrome materials with strong normals. Also tested on UE 5.5, CL: 41545209 and UE 5.6, CL: 45232827 ...
Light Leak Issue in Modular Buildings (Lumen HZBTraversal)
UE - Graphics Features - Lumen - Oct 14, 2025Starting in Unreal Engine 5.6, disabling "r.Lumen.ScreenProbeGather.ScreenTraces.HZBTraversal" can lead to light leaking between adjacent or overlapping meshes. Also tested on Release-5.6, CL: 4523 ...
Incorrect Lumen Scene direct lighting when objects behind masked landscape
UE - Graphics Features - Lumen - Oct 5, 2025When objects are placed behind or beneath a masked landscape and r.Lumen.HardwareRayTracing.SurfaceCacheAlphaMasking is enabled, the direct light evaluation is incorrect. There are two workarounds, ...
Lumen Translucency lighting vs opaque mismatch is larger than expected
UE - Graphics Features - Lumen - Sep 5, 2025The licensee's VFX team has been struggling with getting their Niagara systems with translucent materials to fit into the environments they are being used in. In a project with default settings, the ...
Hardware Lumen Surface Cache Artifacts on Nanite Geometry
UE - Graphics Features - Lumen - Sep 1, 2025When using Hardware Lumen with Nanite-enabled meshes in UE 5.6+, black / dark surface cache artifacts appear that result in generally darker and unstable lighting. These artifacts are not immediatel ...
Lumen Card Sharing is active on material with custom primitive data
UE - Graphics Features - Lumen - Aug 13, 2025The wrong emissive value may be used on Nanite objects with custom primitive data when Lumen card sharing is enabled. This issue can be mitigated with: r.LumenScene.SurfaceCache.AllowCardSharing 0 ...
GPU Crash from out of memory read/writes in Lumen when using non-power-of-2 TracingOctahedronResolution
UE - Graphics Features - Lumen - Aug 6, 2025When the r.Lumen.ScreenProbeGather.TracingOctahedronResolution is not a power of 2 or LumenFinalGatherQuality in a Post Processing Volume is set to a value such that the TracingOctahedronResolution ...
Crash when displaying lumencards on map with many objects
UE - Graphics Features - Lumen - Aug 1, 2025There is a thread conflict between FRDGBuilder execution in Background Worker and LumenVisualizer's LumenCard add/delete process. When lumen cards are displayed in a scene with many objects, a crash ...
Hardware Raytracing on Lumen can cause a crash on AMD Radeon GPUs
UE - Graphics Features - Lumen - Jul 29, 2025Hardware Raytracing support can cause a crash on AMD Radeon GPUs when creating the RT pipeline state. ...
Niagara mesh particles invalidate lighting when "Cast Shadow" is enabled with Hardware Ray Tracing enabled
UE - Graphics Features - Lumen - Jun 24, 2025Lumen HWRT, combined with Niagara Mesh Renderer, can cause the Lumen Scene to be reset, resulting in a sudden change to indirect lighting. ...