Unreal Engine Issues

Mutable COIs built from ChildCustomizableObjects are engine only but do not denote that in anyway.

When creating a Mutable setup with nested Child COs, COIs can result with Editor-Only references, which will cause the COI not appear in the build manifest and the appearance to now spawn in game. ...

Object with "defaultconfig" cannot be edited in Project Settings if their config section exists in DefaultXXX.ini

Notifies placed on the first frame of a montage using root motion don't fire

This is a regression in 5.8 caused by 47265321. It's because we now perform the montage update and dispatch the queued notifies via CharacterMovementComponent::TickCharacterPose.  But that all hap ...

Mover: based movement is unsupported/unsafe on async kinematic backends

Root motion extraction fails on blendspaces with bShouldMatchSyncPhases set

There’s a bug with the bShouldMatchSyncPhases codepath in UBlendSpace::TickAssetPlayer. That codepath calls ResetBlendSamples to give a deterministic output when advancing time on the animations ow ...

Editor crashes when overriding Texture Collection in Material Instance

When a Material uses the DefaultTextureCollection and a Material Instance overrides it - or vice versa - the Editor will crash. Note: bindlessconfiguration=Minimal or higher must be enabled to use ...

Unreal 5.7 Trace server not working on Rocky 8

UnrealTraceServer built on a Rocky 8 machine yields a binary that depends on versions of glibc and glibcxx higher than the 2.28 version provided by Rocky 8.$ ldd UnrealTraceServer./UnrealTraceServer ...

Incorrect rendering result on some geometry and materials in grouped components in SKP imports

Reported in SF [Link Removed] In Twinmotion 2026.1, when importing certain SKP files with grouped components, materials may render incorrectly on some grouped components and will appear with a dark ...

FEvaluateActorReferenceChannels don't run on GameThread

When playing back sequences on a character that is bound users will sometimes run into an ensure from FEvaluateActorReferenceChannels. ...

Shadows become disabled for Datasmith imported lights on resync

Reported in SF [Link Removed] For Datasmith models containing lights, resynchronizing the model after any changes will cause any lights that had shadows enabled prior to the sync to have that setti ...