Constraint Binding ID is broken on attach track when subsequence asset is moved.

UE - Anim - Sequencer - Jan 14, 2026

Moving a level sequence asset that contains actors that are being referenced as a subsequence in an attach track causes the references to drop, even though the subsequence reference is correctly upd ...

Curve Retargeting does not work with SourcePose retarget mode

UE - Anim - Rigging - Retargeting - Jan 14, 2026

Currently we build what source curves we are going to remap is done inside of: FIKRetargetCurveRemapOp::AnimGraphPreUpdateMainThread But in our ikretarget processor code we skip calling that functi ...

Detaching a component may not be replicated to clients

UE - Networking - Jan 13, 2026

Because the archetype for scene/static mesh components has a null value for AttachParent, there are some situations where changes to a replicated component's AttachParent are not replicated to clien ...

Detaching a component with "KeepRelative" location rule can result in incorrect location on client

UE - Networking - Jan 13, 2026

When 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, 2026

The 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, 2026

If 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, 2026

On 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, 2026

Using 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, 2026

At 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 ...