Unreal Engine Issues
Unreal Engine Issues
Body Setup of a Static Mesh with Simple Collision will pass validation, but removing it and using only a Complex collision and setting Collision Complexity "Use Complex as Simple" will fail validation: "Bone None requires at least one collision shape".
UE - Simulation - Gameplay - Oct 20, 2025Context: By default, Unreal Engine creates both simple and complex shapes, then, based on what the user wants (complex query versus simple query), the physics solver will use the corresponding shape ...
HZB Occlusion causes large stalls on the render thread
UE - Rendering Architecture - RHI - Oct 7, 2025HZB Occlusion causes large stalls (greater than 5ms seen) on the render thread due to an RHI flush. This is caused by the following code in FDynamicRHI::RHIMapStagingSurface_RenderThread which force ...
Enabling bUpdateComponentTransformToRootBone in a GeometryCollectionComponent causes broken particles to appear in the wrong location
UE - Simulation - Visual - Jun 22, 2025Enabling bUpdateComponentTransformToRootBone in a GeometryCollectionComponent causes broken particles to appear in the wrong location. When that flag is true, the moment the GeometryCollection (GC) ...
Conflict between sequencer transform track and Parent Constraint from the Animation Mode breaks temporary pivot translation on any actor
UE - Anim - Anim in Engine - Jul 15, 2025Note: This affects all versions from at least UE 5.3, including mainline latest. The "Animation" Editor Mode allows creating constraints for level actors. One of these, the "Parent" constraint, con ...
Translucent materials in the PostMotionBlur pass can cause a flickering viewport artefact when using TAA
UE - Graphics Features - Feb 5, 2025There appears to be a bug relating to rendering multiple windows that can trigger under unknown circumstances. It has been reported on rectangle lights in the forums and on PostMotionBlur materials ...
When breaking a level instance, foliage instances in the LevelInstance are placed in the wrong location
UE - World Creation - Worldbuilding Tools - Level Instances - Jul 8, 2023Following code works as a work around. The code updates placement information of instances. TMap<UFoliageType*, TArray<const FFoliageInstancePlacementInfo*>> AInstancedFoliageActor::GetInstancesF ...
Unexpected behavior when Actor Parenting in the World Outliner of a WP map
UE - World Creation - Worldbuilding Tools - World Partition - Nov 23, 2021Licensee reports the following in the UDN: There seems to be some other erratic behavior when using parenting in world outliner (i.e. drag and drop one actor on another one in world outliner).Since ...
Virtual Memory leak when using specific rendering settings in the template project
UE - Rendering Architecture - Dec 20, 2025When a project is run with these settings in a template project, untracked virtual memory increases. Cvars r.GBufferFormat 3 r.Lumen.TraceMeshSDFs 1 r.Lumen.TranslucencyReflections.FrontLayer.Enab ...
Foliage is placed on LevelInstanceActor does not follow basecomponent when the LevelInstanceActor moves
UE - World Creation - Worldbuilding Tools - Foliage - Jun 24, 2022Foliage usually follows when the Transform of the placed ground or floor changes. However, if the ground or floor is a Level Instance Actor, it will not follow. The cause is in the code below. voi ...
Regression: Several project settings, especially from built-in Plugins, are being silently erased when previously they were not, which is perceived as a bug
UE - Foundation - Feb 28, 2025In UE's Project Settings, some pages are saved automatically to the project's "Config/Default<CATEGORY>.ini" file (meant to be version-controlled) on every change. Other pages have buttons "Set as D ...