Body Setup of a Static Mesh with Simple Collision will pass validation, but removing it and using only a Complex collision and setting Collision Complexity "Use Complex as Simple" will fail validation: "Bone None requires at least one collision shape".

UE - Simulation - Gameplay - Oct 20, 2025

Context: By default, Unreal Engine creates both simple and complex shapes, then, based on what the user wants (complex query versus simple query), the physics solver will use the corresponding shape ...

Children of editor-only actors do not maintain correct transforms when placed inside level instances for PIE and cooked builds

UE - World Creation - Worldbuilding Tools - Level Instances - Oct 20, 2025

We have found an issue where children of editor-only actors get wrong transforms in PIE and cooked builds when placed inside level instances. This affects both engine version 5.5 and 5.6. The issue ...

Inconsistent Nanite raster bin debug visualisation colors

UE - Graphics Features - Nanite - Oct 20, 2025

The raster bin debug colors are not always consistent when a static mesh and spline mesh are present ...

Reimporting of skeletal mesh results in a scrambled skeletal mesh

UE - Editor - Content Pipeline - Import and Export - Oct 17, 2025

When we reimport our skeletal meshes with updated FBXs, the resulting skeletal mesh is scrambled up. See Scrambled.jpg attached. This does not affect every single reimport but happens randomly. W ...

Mutable - morph does not work for a skinned mesh with more than one uv channel

UE - Anim - Mutable - Oct 16, 2025

The morph functionality fails to change when the skinned mesh contains more than one UV channel in a Customizable Object. ...

Right eye looks worse than left with Deferred

UE - Platform - XR - Oct 16, 2025

[Interchange] FBX - Front Facing X-Axis and Flipped Bone Orientation During Animation

UE - Anim - Runtime - Oct 15, 2025

Actors attached to a skeleton imported through a FBX file with the Front Facing X-Axis option enabled are flipped when the skeleton is animated. ...

Intermittent Content is Missing from Cook errors for objects with Niagara packages

UE - Niagara - Oct 15, 2025

Intermittently when cooking large licensee projects, an error is reported at the end of the cook:LogCook: Error: Content is missing from cook. Source package referenced an object in target package b ...

Light Leak Issue in Modular Buildings (Lumen HZBTraversal)

UE - Graphics Features - Lumen - Oct 14, 2025

Starting in Unreal Engine 5.6, disabling "r.Lumen.ScreenProbeGather.ScreenTraces.HZBTraversal" can lead to light leaking between adjacent or overlapping meshes. Also tested on Release-5.6, CL: 4523 ...