Unreal Engine Issues
Unreal Engine Issues
Static Mesh Contact Shadows still render when all LOD sections have Cast Shadows dissabled
UE - Graphics Features - Oct 30, 2025When the cast shadow checkbox is disabled for all sections that make up a static mesh the main shadow is no longer rendered but the contact shadow does not respect the instruction to disable shadows ...
Cloth Asset - Crash when importing morph targets into clothing
UE - Simulation - Visual - Oct 20, 2025The sim morph import has been broken after a change to make it work for cooked assets. Ticking the Import Sim Morph Targets checkbox crashes as soon as a skeletal mesh with morph target is specifie ...
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 ...
Material Instance Platform Stats don't update when Material Layer parameters are changed
UE - Rendering Architecture - Materials - Oct 14, 2025The instruction count appears to update properly if the whole asset editor is closed and reopened. ...
Skylight Leaking Tint in Reflection
UE - Graphics Features - Oct 10, 2025From 5.6 onwards, Skylight Leaking is much stronger in reflections than in the world. Also tested on //UE5/Release-5.6, CL 45232827 ...
HZB Occlusion causes large stalls on the render thread
UE - Rendering Architecture - RHI - Oct 7, 2025HZB Occlusion causes large stalls (greater than 5ms seen) on the render thread due to an RHI flush. This is caused by the following code in FDynamicRHI::RHIMapStagingSurface_RenderThread which force ...
Failed to generate Nanite data for mesh with bDoFastBuild enabled
UE - Graphics Features - Nanite - Oct 1, 2025If "bDoFastBuild" is enabled on a Static Mesh asset, in-editor it will never be able to have Nanite data built for it, preventing the Static Mesh from using Nanite. There is no way to fix this issu ...
Merge Actors (Simplify) is broken with Substrate Shader Models Node
UE - Graphics Features - Substrate - Sep 29, 2025Substrate Materials cannot be baked when Meshes are merged using the "Simplify" method. All textures except for the normal are reduced to a single black parameter. The normal texture produced does n ...
Ray tracing scene doesn't reflect WPO with instance custom data
UE - Graphics Features - Ray Tracing - Sep 19, 2025When custom instance data is used to calculate WPO in a Material and applied to an ISM the WPO value in the Lumen scene (ray tracing scene) is different than the visible scene resulting in incorrect ...
Nanite Skeletal Meshes Invalidate VSM
UE - Graphics Features - Nanite - Sep 17, 2025Nanite Skeletal Meshes will always invalidate VSMs, even with their Shadow Cache Invalidation Behavior set to Rigid. This does not match the behavior of non-Nanite Skeletal Meshes. ...