Unreal Engine Issues
Unreal Engine Issues
Detaching a component with "KeepRelative" location rule can result in incorrect location on client
UE - Networking - Jan 13, 2026When receiving a replicated detachment, USceneComponent::PostRepNotifies will call DetachFromComponent with the KeepWorldTransform detachment rule. If the component is detached on the server with th ...
bWeldSimulatedBodies not replicated with attachment
UE - Simulation - Core - Jan 13, 2026The bWeldSimulatedBodies attachment parameter is not replicated to clients, both in USceneComponent's attachment replication handling and in AActor's FRepAttachment struct. If AttachToComponent is c ...
USceneComponent::AttachToComponent may not be called on client depending on replication order
UE - Networking - Jan 13, 2026If the component being attached is received first, OnRep_AttachParent will set bNetUpdateAttachment to true, so USceneComponent::PostRepNotifies will call AttachToComponent. If the attach parent is ...
HISM flickering when any character is visible
UE - Graphics Features - Jan 12, 2026On an NVIDIA GPU, Instanced Static Meshes can flicker when a Groom card or mesh LOD is visible. This appears related to an issue rendering the ISM into the Scene Depth. At the end of the Prepass, t ...
Light Function Materials containing a Texture Sample and Rotator nodes will fail RHI Validation
UE - Rendering Architecture - RHI - Jan 12, 2026Using a Light Function Material that contains a Texture Sample and Rotator nodes will cause RHI Validation to fail with the following error: LogOutputDevice: Error: Ensure condition failed: Bindings ...
Lumen Global Distance Field Trace Leaking due to Surface Cache Sampling
UE - Graphics Features - Jan 12, 2026At specific distances from a thin wall, surfaces inside of a sealed chamber can receive indirect lighting from outside, leaking light into the chamber. This appears to be due to how SWRT handles sa ...
Temporal blur artifacts on Geometry Cache Components in Blueprint actor
UE - Graphics Features - Jan 9, 2026When a Geometry Collection is in a Blueprint, attached to other components, it can render incorrect motion vectors at some angles. In the test project, any angle that is not a multiple of 45 will re ...
WP Builders: The Datalayer states forced in UWorldPartitionBuilder::LoadDataLayers can be lost
A licensee reported that Datalayers that are added to UWorldPartitionBuilder::IncludedDataLayers in a custom builder PreRun are not respected. I used the minimap builder to debug the state of t ...
Not possible to force the Skeleton attribute to None on a default asset pipeline preset
UE - Editor - Content Pipeline - Import and Export - Jan 9, 2026I guess that when the default value of the pipeline is None, the editor will silently pick the skeleton that is in the same folder of where you are importing. If the UI is active you can then force ...
Velocity Scene Texture Data Integrity Issues
UE - Graphics Features - Jan 8, 2026When a Post-Process Material uses the Scene Texture Material Expression, the following code is generated: ``` MaterialFloat2 Local0 = Parameters.TexCoords[0].xy; MaterialFloat2 Local1 = ClampSceneT ...