Unreal Engine Issues
Unreal Engine Issues
NaN Present on IOS after UE5.6 Because of Removal of MobileSpecularGGX
UE - Platform - Mobile - Sep 24, 2025In UE5.6 MobileSpecularGGX was removed and now mobile devices also run D_GGX. The problem is that there are still cases where very bright values are produced (image 1) and thus NaNs appear in the Bl ...
LevelEditor: "Replace Actor" marks level as dirty even when using external actors
UE - World Creation - Worldbuilding Tools - Jul 15, 2024When using external actors, adding/removing/replacing/editing an actor instance inside a level does not cause any modification to the Level package, which helps reduce contention for the map file on ...
Orientation Warping breaks incoming poses where bones are in component space
UE - Anim - Gameplay - Apr 17, 2025The orientation warping node breaks incoming poses where bones are already in component space. This is because, in EvaluateSkeletalControl_AnyThread, we are repeatedly setting bone transforms direc ...
Orphaned BP actors when using UWorldPartitionBuilder
UE - World Creation - Worldbuilding Tools - World Partition - Nov 21, 2025From an EPS case: --------------------------------- We're seeing a recurring issue where child BP actors are becoming orphaned during any processing that uses UWorldPartitionBuilder. It affects ...
Root motion from montages does not get mirrored correctly
UE - Anim - Gameplay - Dec 2, 2022A customer noticed that root motion did not mirror properly when using montages. The issue is that the root motion mirroring code is only called from FAnimSync::TickAssetPlayerInstances . Th ...
FTickTaskLevel::RescheduleForIntervalParallel Crash
UE - World Creation - Worldbuilding Tools - Oct 11, 2023Short description from Licensee (attached UDN has more info):When streaming a level in and/or out (out especially in World Partition due to the bRequireFullVisibilityToRender variable usage) there i ...
Montage Editor calls NotifyEnds of AnimNotifyState even when paused
UE - Anim - Gameplay - Oct 13, 2023In the Animation Montage Editor, NotifyEnd is unexpectedly called when a time marker is in the middle of an AnimNotifyState and the animation preview gets paused. Because the Animation Montage Edito ...
Translucent Wireframe Materials Exhibit TSR Aliasing/Crawling Due To Incorrect Velocity Rendering When Set to Output Depth And Velocity
UE - Graphics Features - Nov 27, 2025Note that this bug potentially also affects a wide variety of material / geometry setups; however, a translucent wireframe setup is currently the main reproduction case. The issue may also be notice ...
Ambient occlusion causing ghosting for animations when viewport is resized on DX11
UE - Graphics Features - Feb 10, 2025Tested regression against //UE5/Release-5.4 @ CL35576357 and the issue did not occur. This is a confirmed regression.[Image Removed] Jira Bot attaches conversation thread from Slack [Image Removed]D ...
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 ...