When MotionExtrantorModifyer is applied to skeletal mesh, it outputs warning about module loading of AnimationModifierLibrary at editor startup in ThirdPerson C++ project.

UE - Anim - Runtime - Feb 12, 2025

When MotionExtrantorModifyer is applied to a skeletal mesh, it outputs an import error of AnimationModifierLibrary when the editor is launched. The project module and the AnimationModifierLibrary mo ...

FCableSceneProxy::BuildCableMesh thrashes memory allocator

UE - Simulation - Physics - Feb 12, 2025

FCableSceneProxy::BuildCableMesh in CableComponent.cpp:233 showed up as a hot spot in profiling because the two TArray allocators in SetDynamicData_RenderThread used by BuildCableMesh are created an ...

Incorrect mesh deformation when Max World Position Offset Displacement used

UE - Graphics Features - Nanite - Feb 12, 2025

When Vertex Animated Texture is used to animate a mesh with World Position Offset, often the Max World Position Offset Displacement Material setting must be increased or the Bounds Scale increased, ...

Iris - incorrect initial state in pawn's BeginPlay if replicated via huge object path

UE - Networking - Iris - Feb 11, 2025

This occurs when the pawn is initially replicated using the huge object path when first connecting to a server. Destroying and restarting the client's pawn works as expected. After connecting, the c ...

World Partition grid priority setting taken into account last

UE - World Creation - Worldbuilding Tools - World Partition - Feb 11, 2025

From licensee:Editor Grid priorities setting will get overruled in code giving the user false feeling of control – smaller grid cells can load before larger grid cells on the same layer even if the ...

Mover ensure triggered when engine is running in the background

UE - Gameplay - Player Movement - Mover - Feb 11, 2025

When the engine is running in the background, the following ensure may be hit in NetworkPredictionService_Interpolate.inl: npEnsure(ToFrame == INDEX_NONE || LocalFrame - ToFrame < Frames.Buffer.Cap ...

Backwards-compatibility broken for the CDOs of Python-generated Unreal Types because of missing redirectors

UE - Editor - Workflow Systems - Feb 11, 2025

Previously, all Unreal Types generated by python scripts would be created inside package "/Engine/PythonTypes". This was changed by [CL 32478991 in ue5-main branch], which meant to "remove the restr ...

Bug in ULevel::FixupActorFolders.

There is a potential bug in ULevel::FixupActorFolders() in the FixDuplicateFolders section: Suppose you have a folder hierarchy that looks like this:A B(1)B(2) C(1)B(3) C(2) where the letters ...

Regression: FAnimInstanceProxy memory leak when BeginDestroy() called on UAnimInstance before USkeletalMeshComponent

UE - Anim - Runtime - Feb 10, 2025

In UE 5.5, the fix applied by CL 36529858 in ue5-main updated USkeletalMeshComponent::ClearAnimScriptInstance() to call AnimScriptInstance::UninitializeAnimation() on the animation instance. This, i ...

Add Substrate Material Support to Lumen Performance Overview

UE - Graphics Features - Substrate - Feb 10, 2025

There is a discrepancy when inspecting Substrate materials in the Lumen Performance Overview. Compared to viewing non-Substrate materials the overview show all surfaces in red indicating that Lumen ...