Unreal Engine Issues
Unreal Engine Issues
Editor/Details Panel allows duplicate keys in TMap/TSet UPROPERTY()
UE - Editor - Workflow Systems - Sep 5, 2023When edited through the Details Panel in the Editor, TMap and TSet properties should not allow duplicate keys. When those keys are USTRUCTs with the “WithIdenticalViaEquality” trait, this should be ...
Dithered LOD transitions sometimes briefly flicker to the next LOD before fading
UE - Graphics Features - Jun 12, 2025When dithered LOD transitions occur, a brief flash of the next LOD level is first shown on the entire mesh after which the current LOD fades to the next (or previous) LOD. The flashing behavior only ...
Datasmith Export Bug with Camera Target
UE - Editor - Content Pipeline - Datasmith - Exporters - Mar 7, 2025Potential bug was encountered when exporting vray cameras and their targets that have been path-constraint to corresponding splines. The resulting export file shows no camera targets; hence, missing ...
BlackboardComponent observer can be called for the wrong key
UE - AI - BehaviorTree - Feb 7, 2023We need to, at least, prevent this by clearing observers when running a new BT using a different blackboard. Must also think that this might affect licensees relying on the current behavior (might h ...
Crash when using CastChecked<>(nullptr, ECastCheckedType::NullAllowed) in configurations where checks are disabled
UE - CoreTech - Jun 19, 2025When using CastChecked<>(), the second parameter can be passed as ECastCheckedType::NullAllowed to make the check succeed when the input is nullptr. However, in UE 5.5 up to the latest engine versio ...
VALIDATE_UNIFORM_BUFFER_LIFETIME fails compilation
UE - Graphics Features - Jul 24, 2025Also verified on Release-5.5.4 CL 40574608 ...
ULevelSequence trying to duplicate a REINST_ class when creating new custom binding in ConvertOldSpawnables()
UE - Framework - Blueprint Compiler - Jul 23, 2025The assert that we're hitting is:Cannot replace existing object of a different class. New Object: /Engine/Transient.REINST_BPC_NPC_VFX_C_230 /Game/Maps/[REDACTED]/Levels/[REDACTED]/LevelSequence/ ...
FPS drop (present time increase) when moving the editor windows to secondary screens
UE - Rendering Architecture - RHI - Apr 29, 2022The licensee has mentioned that they also see an FPS drop without a second monitor, so this can happen just by separating windows out on the same screen. ...
Lumen ignores Landscape Holes (Landscape Visibility) when Hardware Ray Tracing is enabled and Ray Lighting Mode is set to Surface Cache
UE - Graphics Features - Ray Tracing - Jan 31, 2025Context Lumen is the default global illumination and reflections system. Lumen renders diffuse interreflection with infinite bounces and indirect specular reflections in large, detailed environments ...
Modifying the properties of a ChildActorComponent in a child blueprint can modify the parent actor ChildActorComponent properties.
UE - Framework - Blueprint - Dec 10, 2024When a property of a ChildActorComponent is modified in a child class, the parent ChildActorComponent class can also get modified. This happens when the Parent blueprint actor has a ChildActorCompo ...