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 ...

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 ...

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 ...

DMX component in world partitioned level fails cook

UE - Virtual Production - IO - DMX - Feb 10, 2025

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 : ...

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

UE - AI - Navigation - Feb 7, 2025

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

[Interchange] Crash on asset re-import

UE - Editor - Content Pipeline - Import and Export - Feb 7, 2025

We've started seeing a crash in editor when re-importing one of our assets. <pre class="ql-syntax">Assertion failed: (Index >= 0) & (Index < ArrayNum) [Link Removed] [Line: 783] Array index out of ...

[AI] Navmesh tiles on different layers get removed while streaming out in WP Dynamic Modifiers Only navmesh

UE - AI - Navigation - Feb 6, 2025

 Streaming out the navmesh and streaming the area back into the world before the GC runs causes the navmesh streamed back into the world to only have navmesh tiles on a layer with tiles that would b ...