Unreal Engine Issues
Unreal Engine Issues
Incorrect Lumen Scene direct lighting when objects behind masked landscape
UE - Rendering - 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, ...
Non-determinism in StaticMeshComponent::BodyInstance when cooking LevelInstances
UE - Runtime - Simulation - May 21, 2026A licensee reported that serialization of LevelSequence with StaticMeshActor with default collision for which mesh has NoCollision profile is not deterministic. The issue seems to be in the fact tha ...
(BUG) Sequencer Root motion breaks down when using SwapRootWithActor, translation track and transform origin actor
UE - Anim - Anim in Engine - Jul 19, 2024When "Sequencer.ThreadedEvaluation.AllocationThreshold 8" is initiated, characters in a level sequence that have “Swap Root Bone Actor” activated on their animation will begin to slide very fast acr ...
Screen Space Ambient Occlusion Artifacts
Docs - Samples - Apr 3, 2015Flickering occurs when using the Post Process Ambient Occlusion (Screen Space AO). This is more noticeable when using stronger values entered into the AO fields. I checked these settings in both 4 ...
Trace complex for assets simulating physics does not show accurate collision
UE - Gameplay - Apr 27, 2015When using Trace Complex in a LineTraceByChannel node does not give accurate results when object is simulating physics and scaled. The scaled root mesh in the BP will only register its collision rat ...
Teleporting to the World Location of a Scene Component in a packaged game will crash the game
UE - Gameplay - Blueprint - Jun 1, 2015Teleporting to the World Location of a Scene Component in a packaged game will crash the game. Teleporting to the Actor Location does not cause this crash. Crash log attached. Nothing is showing up ...
BulkData Async loading remains in memory
UE - Foundation - Core - Oct 26, 2016Gil's new loading path may already walk away from this issue. But here's some thing I tested locally if we want to fix this. A simple way to fix is to simply add BulkDataAsync.Deallocate(); ResetA ...
Destructible Mesh spawned before static mesh with World or Asset support is not supported
UE - Simulation - Physics - Destruction - Apr 27, 2015When using World Support or Asset Defined Support on a Destructible mesh that is spawned in, if the static world geometry is spawned in after the DM it will not be supported. However, if the static ...
VC Runtime not in UnrealLightmass temp directory; causing lightmass build errors
UE - Foundation - Cpp Tools - UnrealBuildTool - Oct 14, 2015A Redistribute file for VS 2015 is needed to build lightmass, but this is not currently included with the engine. If a user does not have VS 2015 installed, lightmass will fail with this error: Un ...
Pasted material function nodes lose their connections
UE - Rendering - Architecture - Materials - Dec 3, 2019The fix for [Link Removed] caused a regression where links to material nodes no longer carry over when a group of nodes is copied and pasted ~ User submitted Image and repro steps appended. I conf ...