Unreal Engine Issues

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

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 ...

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

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 ...

Mover ensure triggered when engine is running in the background

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

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

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

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 ...

DMX component in world partitioned level fails cook

Since UE5.5, RegisterComponent has been called during cook process, So unnecessarily references from DMXLibrary to DMXComponent has been added.  There is a workaround to avoid adding references : ...

Converting a modular character to a static mesh can result in a crash or in an asset with corrupted data

[AI] Navigation System can be constructed in situations where the NavigationObjectRepository subsystem is not valid

Investigate and fix all calls where the Navigation System is constructed without the NavigationObjectRepository subsystem being valid.  ...