Texture Streaming can randomly streams in all Mips, causing large memory spikes

UE - Graphics Features - Dec 5, 2025

A possible race condition allows texture instance views to read uninitialized bounds, causing either garbage or zero screen size values to be returned by FRenderAssetInstanceAsyncView::GetRenderAsse ...

Issue with Niagara emitter inheritance

UE - Niagara - Dec 4, 2025

Modules in the particle spawn stage get unlocked and lose inheritance after changing the inherited emitter's interpolated spawn mode to "No Interpolation" then resetting. ...

Morph target is not applied on the first frame in Level Sequence

UE - Anim - Runtime - Dec 4, 2025

When a skeletal mesh with morph targets spawns in the sequence, the morph is not reflected in the first frame.  It appears that in the SkeletalMesh ProcessStage_SkinCache call, MorphVertexBuffer- ...

UInstancedStaticMeshComponent::AddInstances does not appear to be adding per-instance previous transforms when enabled

UE - Graphics Features - Dec 3, 2025

Instanced static mesh component does not add instances transforms to PerInstancePrevTransform array when using UInstancedStaticMeshComponent::AddInstances. Additionally Updating the transforms of th ...

Unreal Engine Fails to Launch with Vulkan SM6 RHI and RenderDoc Auto-Attach Enabled

UE - Rendering Architecture - RHI - Dec 3, 2025

When launching Unreal Engine with the Vulkan RHI, SM6 and RenderDoc Auto Attach on Startup enabled, the engine fails to initialize with the error: “A compatible Vulkan Driver is required to run the ...

Pass names appear as "RDGEvent" in Unreal Insights when r.rhisetgpucaptureoptions=1

UE - Rendering Architecture - RHI - Dec 2, 2025

When capturing a trace in Unreal Insights, all r.rhisetgpucaptureoptions=1 (r.RDG.Events=3) all RDG pass events appear simply as RDGEvent, without the actual name due to the logic for RDG_EVENT_SCOP ...

FStateTreeRunParallelStateTreeTask and TStateTreePropertyRef

UE - AI - StateTree - Dec 2, 2025

When using a state tree that has a StateTreePropertyRef as a parameter in parallel any references will fail to resolve using the GetPropertyRef node. ...

Chaos sometimes can not generate contact points while two dynamic convex hulls actually collide. It results in instability in the contact behavior​ - such as jittering, inconsistent contact forces, or unexpected collision responses.

UE - Simulation - Core - Dec 2, 2025

Context: Chaos Physics is able to use convex hulls to represent object collision geometry for queries and simulation. Problem: Chaos sometimes can not generate contact points while two dynamic conv ...

Not all MidPhases are enumerated in TSimCallbackObject::OnMidPhaseModification

UE - Simulation - Core - Dec 2, 2025

Newly generated MidPhases are copied into the array accessible in the NarrowPhase after the OnPreSimulate callback is invoked. As a result, it is not possible to modify newly created MidPhases withi ...

Not all MidPhases are enumerated in TSimCallbackObject::OnMidPhaseModification

UE - Simulation - Core - Dec 2, 2025

Newly generated MidPhases are copied into the array accessible in the NarrowPhase after the OnPreSimulate callback is invoked. As a result, it is not possible to modify newly created MidPhases withi ...