Unreal Engine Issues
Unreal Engine Issues
AutoSize triggers ensure on shortened Skel Anim Section moved past anim length
UE - Anim - Sequencer - May 26, 2026In Sequencer, calling "Edit > Auto Size" on a UMovieSceneSkeletalAnimationSection triggers the LowerBound > UpperBound ensure in UMovieSceneSection::SetRange (MovieSceneSection.h:333) when the secti ...
FNiagaraRendererMeshes::GetDynamicRayTracingInstances(...) corrupting GPUScene when rendering multiple views
UE - Rendering - Graphics Features - Ray Tracing - May 20, 2026When rendering a game in splitscreen using Lumen HWRT, Nanite and a large number of Niagara Mesh Particles 1mil+, various meshes and actors will stop rendering. Setting r.RayTracing.Geometry.Niagar ...
ApplyLocalExposure uses Output_ExtentInverse instead of Output_ViewportSizeInverse for bilateral grid UV
UE - Rendering - Graphics Features - May 18, 2026The ApplyLocalExposureCS shader in PostProcessLocalExposure.usf computes UV coordinates for the LumBilateralGrid 3D texture using Output_ExtentInverse (1/RenderTargetSize) instead of Output_Viewport ...
[Enhanced Input] Chord trigger fails when its referenced action lives in a lower-priority IMC
UE - Gameplay - Input - May 18, 2026Summary A UInputTriggerChordAction does not fire when the action it references (the "chording action") is mapped in a different Input Mapping Context with a lower priority than the IMC containing the ...
check(bRenderStateCreated) fires in SendRenderDynamicData_Concurrent called from FRegisterComponentContext::Process
UE - Rendering - Architecture - RHI - May 18, 2026FRegisterComponentContext::Process() in ActorComponent.cpp iterates over SendRenderDynamicDataPrimitives and calls SendRenderDynamicData_Concurrent() on each. The existing guard checks ::IsValid(Pri ...
Meshes with scaled root bones pop when entering simulation
UE - Runtime - Simulation - May 15, 2026This issue is fallout from the changes in 33851494. Prior to that, we didn’t get the pop on beginning the sim. The problem appears to be that in USkeletalMeshComponent::PerformBlendPhysicsBones we ...
Visibility track key value is no longer the inversion of the bound bHidden property
UE - Anim - Sequencer - May 13, 2026Regression introduced in UE 5.7. Works correctly in UE 5.6. Up to UE 5.6, the bool value written to the Visibility track's BoolCurve was the inversion of the underlying bound property (e.g. AActor: ...
Resavepackages commandlet strips level package thumbnails
UE - Editor - Developer Usability - May 12, 2026When loading thumbnails in FLinkerLoad::SerializeThumbnails, the level asset has two thumbnails. The first one has a size of 0, which causes the loading process to abort early. Since the actual thum ...
Material parameters flickering due to UMG animation switching and multi-threaded execution
UE - Editor - UI Systems - UMG - May 12, 2026When continuously transitioning to UMG animations that have a track targeting the same material parameter within the UUserWidget::OnAnimationFinished event, the number of source inputs to UMovieScen ...
Chaos FieldSystem examples in the engine content add field nodes every Tick, which creates too many components
UE - Runtime - Character - May 5, 2026Can we add the field on construction instead of on Tick to avoid the performance overhead caused by creating too many components? ...