Unreal Engine Issues
Unreal Engine Issues
GeometryCache: data race between FGeometryCacheSceneProxy::CreateHitProxies and the render-thread FrameUpdate enqueued by the proxy constructor
UE - Rendering - Architecture - Oct 13, 2026Symptom An intermittent ensureMsgf fires in the editor when a level contains a UGeometryCacheComponent: Array has changed during ranged-for iteration! (TArray ranged-for iterator check, Array.h). T ...
Montage preview does not stop the previous montage from another slot group
UE - Runtime - Animation - Oct 5, 2026In the Animation Editor, when you open a montage that uses a different slot group, the previous montage keeps playing in the preview, and its notifies keep firing. If both montages have a section wi ...
Camera Component - Regression in Unreal 5.7+
UE - QA - Support - Oct 4, 2026POST BODY:Summary Hey there - I’ve been sticking with Unreal Engine 5.6 for cinematics because of a regression that's been made to CineCameraActors (specifically the CameraComponent nested inside of ...
ResolvedView.DirectionalLightColor and DirectionalLightDirection go black when one of several directional lights is removed from the scene
UE - Rendering - Features - Sep 25, 2026With more than one directional light in the scene, ResolvedView.DirectionalLightColor and ResolvedView.DirectionalLightDirection can report the wrong light, or black and a zero vector, while a direc ...
Enhanced Input: use-after-free in EvaluateInputComponentDelegates when a delegate forces a synchronous mapping rebuild
UE - Gameplay - Input - Sep 21, 2026Context UEnhancedPlayerInput::EvaluateInputComponentDelegates iterates the delegates that triggered this tick. For each one it resolves the action's state via FindActionInstanceData(DelegateAction) ...
Open Formats: USD UX - Visibility managemente in USD Stage Actor
UE - VEI - Open File Formats - Sep 15, 2026Working with a big USDStageActor is complicated due to visibility management. We are importing "simple" environments from usd files through the USDStageActor. However, when the artist wants to hide ...
Open Formats: Import - Issue with importing alembic files: the skeletal mesh asset doesn't contain LOD description
UE - VEI - Open File Formats - Sep 15, 2026Helloo everyone!! 😄 We are experiencing an issue with importing skeletal meshes from alembic. For reference, this issue happens in vanilla engine 5.7.4, but it doesn't occur in versions 5.6.x. 1) ...
TMap where key is an FString: initializer list will accept bad MakeTuple
UE - Core - Systems - Sep 2, 2026POST LINK: https://forums.unrealengine.com/t/tmap-where-key-is-an-fstring-initializer-list-will-accept-bad-maketuple/2747443 POST BODY:Summary A TMap where the key is an FString can be created lik ...
[Mutable] Morph Targets can be disabled in packaged builds when Mesh Streaming is enabled
UE - Runtime - Mutable - Aug 28, 2026When a Mutable mesh instance is created while the actor spawns at a distance, only the low LODs are generated, and the mesh is created with no Morph Targets registered. Later, when the camera approa ...
FCameraShakePreviewer retains world-outered UCameraShakeBase instances indefinitely, fataling CheckForWorldGCLeaks on editor map change
UE - ACT Character - Sequencer - Aug 21, 2026FCameraShakePreviewer is an FGCObject that strongly references the UCameraShakeBase instances it previews, and creates them outered to the previewed UWorld. Nothing releases them on world teardown, ...