Cloth rendering issue on triangles sharing kinematic attachments.

UE - Simulation - Physics - Character - Jul 29, 2020

All render vertices on any cloth triangle that contains one or two fixed vertex are set as fixed, whereas this should only be the case if all three vertices were fixed. ...

Some post-processing passes sample outside of the viewport when using scene capture components

UE - Rendering - Features - Nov 29, 2023

It looks like the SSAO shader does not clamp its sample space to the half view size for the two inputs "Ambient Occlusion" and "AmbientOcclusionSetup", leading to invalid data entering the edge of f ...

Renaming a custom component code class and performing a Hot Reload will cause the Editor to crash when a Blueprint containing an instance of that component class is opened.

UE - Gameplay - Blueprint - Nov 26, 2014

Renaming a custom ActorComponent class when that class is set as a component in a Blueprint and performing a Hot Reload will crash the Editor if the Blueprint is opened for editing after the project ...

Destroying Actor via RepNotify After Seamless Travel Causes Pending Kill Warning

UE - Networking - Dec 15, 2016

Attempting to destroy an actor via a repnotify after seamless travel is causing the actor to fail to be destroyed because of a pending kill warning: [2016.12.15-19.10.13:936][574]LogNetPackageMap:W ...

Calling DiscardPlayerInput() does not appear to actually discard the player's input

UE - Gameplay - Jun 19, 2018

Calling DiscardPlayerInput() does not appear to actually discard the player input. The comment for the function indicates that input will be consumed and discarded without doing anything with it. Ho ...

bIgnoreAllPressedKeysUntilRelease behaves differently for triggers in EnhancedInputAction and triggers in InputMappingContext

UE - Gameplay - Input - Aug 10, 2023

For actions that are triggered on the Input mapping context, simply adding or removing an InputMappingContext with no related key override with the bIgnoreAllPressedKeysUntilRelease option will caus ...

Hardware Lumen Surface Cache Artifacts on Nanite Geometry

UE - Rendering - Features - Lumen - Sep 1, 2025

When using Hardware Lumen with Nanite-enabled meshes in UE 5.6+, black / dark surface cache artifacts appear that result in generally darker and unstable lighting. These artifacts are not immediatel ...

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 - Runtime - Simulation - 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 ...

[Landscape] weightmap layer allocations leak into left/top/top-left neighbor components

UE - Graphics Tools - Terrain - Landscape - Oct 13, 2026

In 5.8, weightmap layer allocations of a landscape component leak into its left, top and top-left neighbor components when Edit Layers are merged. Neighbors end up with layers that were never painte ...

[MetaSounds] - Input Parameter Settings revert to the default after a MetaSound becomes virtual

UE - Audio - Sep 23, 2022

On restarting from Virtualizing, any parameters set previously on a MetaSound are ignored and the MetaSound restarts with the default values. This does not behave this way with Sound Cues, in which ...