RuntimeCellTransformers can result in increasing the instance count when a BP instance is not destroyed.

UE - World Creation - Worldbuilding Tools - Oct 22, 2025

The problem is related to the SimpleConstructionScript that executes on the BP instances after the transformer.  The problem also happens at cook time as the SCS is executed when the package is sav ...

World Position Offset invalidates Point Lights Entire Virtual Shadow Map Cache when light frustrum is only overlapping a small portion of the mesh

UE - Graphics Features - Oct 22, 2025

When adding a spotlight to the scene it does not correctly use cached virtual shadow map pages when the spotlight overlaps a mesh using WPO. This can be most easily observed by entering 'Cached Pag ...

Child actor components fail to attach in cooked builds when mobility is set to movable and end up at the origin

UE - Gameplay - Oct 21, 2025

Context: A Child Actor Component allows an actor in Unreal Engine to contain another actor as its child (component). Problem: The problem is inconsistent handling of child actor component mobility ...

Mover character no longer calls ProduceInput on server when the only client unpossesses it and disconnects

UE - Gameplay - Player Movement - Mover - Oct 21, 2025

When a client disconnects/unpossesses a mover character, the character's Network Prediction Component will re-configure itself now that it does not have a net connection. However, this handling will ...

Video material broken on Mac

TM - Rendering - Oct 21, 2025

On Mac devices, the video material in the viewport will display incorrectly, appearing stretched significantly. This only seems to affect the viewport and not rendered exports. ...

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 ...

[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. ...