Multiple setter functions in UMaterialEditingLibrary always return false even when the parameter is correctly set on the MaterialInstance.

UE - Rendering - Architecture - Materials - May 30, 2025

In Unreal Engine, materials can expose parameters that can then be modified via instances (MaterialInstanceConstant). The UMaterialEditingLibrary provides several functions to modify these parameter ...

ChaosWheeledVehicleMovementComponent is breaking the const CDO contract and changes to the instances are being applied to the CDO

UE - Runtime - Character - Apr 28, 2025

As described by the licensee, the const CDO contract is being broken on ChaosWheeledVehicleMovementComponent. The issue the licensee is facing is that by spawning cars with different configurations, ...

Inconsistent parameter handling for pak/iostore block size / patch padding

UE - CoreTech - IoStore - Apr 14, 2025

Users have trouble overriding the blocksize/patchpaddingalign parameters for UnrealPak from UAT commandlines.There is no easy way to specify these parameters through a buildcookrun, instead they n ...

VisualizeTexture with the BMP flag causes a crash when any mip over mip0 is requested

UE - Rendering - Architecture - Dec 18, 2024

When a mip level higher than 0 is requested in VisualizeTexture, the engine will crash. The root cause appears to be VisualizeTexture.cpp:924, on which an incorrect mip level is used to read a non-m ...

CharacterMovementComponent - Jump incorrectly simulated when moving against a wall, resulting in an apex height lower than expected and framerate-dependent

UE - Gameplay - Player Movement - Jun 17, 2024

The CharacterMovementComponent simulates the position of a jumping/falling character inside function UCharacterMovementComponent::PhysFalling() [CharacterMovementComponent.cpp:4381]. On the main cod ...

SpringArmComponent with "Use Camera Lag Substepping" does not handle fluctuating frame rates correctly

UE - Gameplay - Jun 4, 2024

The description of SpringArmComponent's "Use Camera Lag Substepping" option says "sub-step camera damping so that it handles fluctuating frame rates well". However, as noted and explained by a licen ...

Nanite mesh shadows not updating when CSMCaching enabled

UE - Platform - Mobile - May 25, 2024

A Nanite primitive casting a CSM shadow on another Nanite primitive with "Cast Shadows" disabled, will have it's shadow disappear completely when r.Shadow.CSMCaching = 1. ...

On NM_Client, GameplayDebugger defaults to green smiley for NPCs implying running BehaviorTree while AI info is unknown

UE - AI - Debugging - Mar 12, 2024

Context GameplayDebugger (Press ` in-game) displays a green smiley (AICON-Green) for AIControlled pawns that are running a BehaviorTree and a red angry face (AICON-Red) otherwise. If the AIControll ...

Placing a section at the end of montage is not properly handled

UE - Anim - Gameplay - Feb 24, 2024

Placing a  section at the very end of a montage with no duration or animation assigned after it is not properly handled.  Normally sections with 0 length are skipped and search continues since they ...

UNetDriver server-side hitch results in ActorInfo->NextUpdateTime far into future

UE - Networking - Feb 16, 2024

A high UWorld::Tick DeltaSeconds (i.e. GameThread hitch) results in a high UNetDriver::TickFlush DeltaSeconds. This DeltaSeconds can high (many seconds) if the hitch is long. This value then affects ...