Unreal Engine Issues
Unreal Engine Issues
Instanced Actors: PCG on RuntimeGrid "None" assigns created IAManagers RuntimeGrid "MainGrid", causing cross-grid reference
UE - World Creation - Procedural Tools - PCG Graph - May 30, 2026Context PCG can be used to spawn Instanced Actors via the PCG IA Interop plugin, that makes Spawned Instanced Actors available as node. When a PCGActor placed in the level runs a PCG graph that spa ...
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 ...
Lumen lighting in Presentations may appear darker than in Viewport
TM - Rendering - May 22, 2026Reported in SF [Link Removed] In some scenes with Lumen enabled, interior scene lighting without direct lighting can appear drastically darker in Cloud Presentations than they do in the editor view ...
StreamingGeneration: Actor desc mutator phase now writes ActorDescView directly, breaking the cluster-invariant check in ValidateContainerInstanceDescriptors
UE - World Creation - Worldbuilding Tools - World Partition - May 22, 2026This report is from an EPS case: We hit a regression upgrading our project from 5.7 to 5.8. Map Check (and any other path that ends up calling UWorldPartition::CheckForErrors) assert inside FWorld ...
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 ...
Twinmotion sign-in error when attempting sign-in inside app
TM - Core - May 18, 2026Reported in SF [Link Removed] Attempting to sign into Twinmotion from within the TM 2026.1 editor results in a consistent sign-in error using the sign-in buttons. Initial sign-in during launch whe ...
iOS builds fail on Windows.
UE - Platform - Mobile - May 15, 2026Loading Windows installed iOs mobile provisioning profiles fails at start of iOS build from windows machine. This due to a recent change that attempts to load PKCS12 from mobileprovision files. Thes ...
Imported Substance materials behave incorrectly when applying UV rotation
TM - Tools - May 14, 2026Reported in SF [Link Removed] and on the forums at https://forums.unrealengine.com/t/substance-3d-materials-not-reflecting-light-properly/2718611 UV rotation behavior is incorrect for Substance mat ...