Packed Level Actors will create ISMs with inverted normals when a portion of static meshes have negative scales. This is apparent with two-sided materials.

UE - World Creation - Worldbuilding Tools - Feb 17, 2025

Packed level actors will create ISM instances with inverted normals when the selection of meshes used to create the packed level actor contains a subset of meshes with negative scales. This is the ...

Performance slowdown when ray tracing is disabled due to SetResidencyPriority

UE - Rendering Architecture - RHI - Jul 17, 2025

When a game is compiled with ray tracing disabled (D3D12_RHI_RAYTRACING=0) and the GPU the game is running on becomes low on VRAM, frame time is negatively impacted and doesn't recover. The D3D12_RH ...

LIVE: Setting sg.EffectsQuality between values will reset Destructible meshes if they have fractured

UE - Simulation - Physics - Destruction - Nov 14, 2014

DESCRIPTION: Using the command line sg.EffectsQuality and setting a value will reset a destructible mesh if it has already been fractured. AH Post: https://answers.unrealengine.com/questions/12850 ...

C# UHT fails to recognize delegates declared in another class's namespace

UE - Foundation - Cpp Tools - UnrealHeaderTool - Dec 14, 2022

Repro Rate: 3/3 This issue occurs in the live build //UE5/Release-5.1 at CL 23058290. This issue has also been regression tested against //UE5/Release-5.0 at CL 20979098 and is confirmed to be a r ...

Crash when duplicating component with Instanced property initialized with CreateDefaultSubobject

UE - Framework - Feb 2, 2024

An editor crash can be observed when copy-pasting an actor with an actor component with an instanced object property when set to a non-default value. Detailed steps to reproduce are provided below. ...

Crash on Mac when adding Convex Collision to a mesh converted from a brush

UE - Platform - Apple - Jun 6, 2017

This is one of the top Mac crashes occurring in 4.16. Caused by adding Auto Convex Collision to a mesh converted from a brush. Does not occur on Windows. User DescriptionsI was trying to add a conv ...

Skeletal Meshes have physics collisions lag

UE - Simulation - Physics - Oct 2, 2019

Skeletal mesh's physics collision lag behind the actual mesh. It didn't matter if there was just a root bone or multiple bones/constraints. This doesn't happen when using static meshes. The effect ...

[Interchange][gltf] Imported animation are all 1 frame long.

UE - Editor - Content Pipeline - Import and Export - Jan 27, 2025

All the imported animation only contain one frame. If the file contains in archive are imported in a gltf web viewer we can see animation are playing.  [Link Removed] [Link Removed] https://foru ...

ARKit GetCurrentFrame crashes app

UE - Platform - XR - Aug 22, 2018

Using "GetCurrentFrame" crashes app. "The crash is due to the default constructor of FAppleARKitFrame being called by the above mentioned blueprint function. That constructor fails to initialize fi ...

[AI] Updating an HISM instance transform breaks the navmesh on all of the HISM instances.

UE - AI - Navigation - Jan 19, 2024

Navmesh does not generate correctly around HISM instances when one instance has its transform updated. The most noticeable change is that adjusting the scale of an instance's transform will cause th ...