Unreal Engine Issues
Unreal Engine Issues
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 ...
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, ...
TMatrix<T>::InverseFast() ensure when running URootMotionModifier_SkewWarp::WarpTranslation().
UE - Anim - Gameplay - Oct 3, 2025URootMotionModifier_SkewWarp::WarpTranslation() uses InverseFast() within a block of code that is only executed if DeltaTranslation is not nearly zero. The ToRootSyncSpace transform the code builds, ...
Wrong density calculation in UBodySetup::CalculateMass
UE - Simulation - Core - Sep 29, 2025Wrong density calculation in UBodySetup::CalculateMass. The licensee has provided the following analysis and suggested fix: In UBodySetup::CalculateMass, the following code is present: // physical ...
Custom Depth range is different than Pixel Depth range
UE - Rendering Architecture - Shaders - Sep 25, 2025Shaders that compare custom depth and pixel depth get wrong output values because the ranges are different. This error is most noticeable over large distances. The difference in ranges is due to t ...
Post Process Animation Blueprint Crash When Using Blend Node
UE - Anim - Runtime - Anim Blueprints - Sep 24, 2025When using a Blend node inside a Post Process Animation Blueprint, the editor crashes while rendering thumbnails. The crash occurs because USkeletonThumbnailRenderer attempts to draw a thumbnail wit ...
When exporting static meshes with bExportSourceMesh enabled, there is a problem where all UVs are fragmented.
UE - Editor - Content Pipeline - Import and Export - Sep 22, 2025From customer: "In the StaticMesh Export option, when bExportSourceMesh is set to True, exporting StaticMesh Assets and importing them into DDC tools such as 3dsMax or Maya results in the UVs being ...
Controller::OnPossessedPawnChanged broadcasts (Pawn->null) but not (null->Pawn) during AGameModeBase::RestartPlayer()
UE - Gameplay - Sep 17, 2025Context AController has a blueprint assignable delegate that fires when the possessed pawn changes. This should fire in both singleplayer and networked games. The bug is reproducible in single play ...
Point light missing issue on PowerVR GE8xxx when GPUScene is enabled
UE - Platform - Mobile - Sep 17, 2025On PowerVR GE8xxx devices (e.g., GE8320), running with GPUScene enabled on the OpenGL ES path, point/local Lights render nothing or significantly weak result. Withouy GPUScene(UniformView/UBO path), ...
FBX reimport issue with Interchange Framework
UE - Editor - Content Pipeline - Import and Export - Sep 15, 2025A licensee has reported that the following repro steps can result in a "Failed to merge bones" error:One of our Skeletal Mesh assets was imported into engine version 5.4 using an older version of th ...