Unreal Engine Issues
Unreal Engine Issues
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 ...
APT copies only one CSV from GauntletTemp even if multiple perf sequences are run
UE - Platform - APT - Oct 8, 2025Reported by a licensee - separate CSVs from different perf sequences that are in one go are not picked up upon completion. ...
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. ...
Local Exposure can cause large variations in PreExposure under certain conditions
UE - Graphics Features - Sep 16, 2025PreExposure is influenced by LocalExposure in PostProcessEyeAdaptation.cpp:1265. It appears when the scene is particularly dark and using manual exposure, the LastAverageLocalExposure can read a lar ...
Custom fallback mesh LODs for Nanite-enabled meshes not working
UE - Graphics Features - Sep 15, 2025Creating a custom fallback mesh with LOD for Nanite-enabled meshes with multiple materials, results in mesh LODs with errors. As the number of material sections (material slots) decreases with coars ...