Iris - large fast arrays serialize multiple elements when only one is dirtied

UE - Networking - Iris - Apr 8, 2025

This seems to be a result of how the changemask is handled for fast arrays. Because the changemask is a fixed set of bits (defined by IrisFastArrayChangeMaskBits), a single bit can represent multipl ...

Incorrect volume bounds check in FTranslucentLightInjectionCollector::AddLightForInjection

UE - Graphics Features - Apr 8, 2025

The 'VolumeBounds' array in FTranslucentLightInjectionCollector::AddLightForInjection is accessed as a pointer instead of with 'VolumeCascadeIndex' and thus fails bounds checks for the outer volume. ...

Overlay materials stop working when Show Collisions

UE - Simulation - Physics - Apr 7, 2025

Overlay Materials are disabled when the Collision showflag is enabled. ...

Lack of multi-bounce when using software traced lumen radiosity

UE - Graphics Features - Lumen - Apr 4, 2025

Certain Lumen Hardware Ray Tracing CVars, when disabled in isolation, will not fall back to tracing the Global Distance Field, because the Global Distance Field is still disabled. The function "Lum ...

Sequencer Conditions crash - GarbageCollectionVerification

UE - Anim - Sequencer - Apr 3, 2025

Encountered a crash during the garbage collection phase when using sequencer conditions with subsequence tracks. Specifically, objects appear to break the "Disregard for GC" assumptions. ...

Video material previews incorrectly on Mac

TM - Rendering - Apr 3, 2025

Received multiple reports of users on Mac computers experiencing issues previewing video materials in Twinmotion 2025.1. When adding video materials to the scene, the scale seems to be incorrect an ...

MaterialX texture imports won't import files with the same name

UE - Editor - Content Pipeline - Import and Export - Apr 2, 2025

Hello! When importing .mtlx files that contain textures with the same name (but different filepaths), only the first texture is imported. This seems to be due to the function CreateTextureNode() i ...

Issue when sampling landscape height at a given location using Chaos::FHeightField::GetHeightAt

UE - Simulation - Physics - Apr 2, 2025

This is an issue reported from a licensee: When sample landscape height at a given location, it is likely we interpolate from the wrong triangle. [Image Removed] Details in: [Link Removed] ...

Crash when Undo after deleting a Material Layer of a Material Instance.

UE - Rendering Architecture - Materials - Apr 2, 2025

In Unreal Engine version 5.5.4, the Editor crashes when performing Undo after deleting a Material Layer of a Material Instance ...

Rect light LTC textures fail to load when cooking with bSharedLinearTextureEncoding enabled

UE - Texture - Apr 2, 2025

When running a build with bSharedLinearTextureEncoding enabled, View.GGXLTCMatTexture and View.GGXLTCAmpTexture are pointing at the black texture fallback, which affects correctness of rect lighting ...