Unreal Engine Issues
Unreal Engine Issues
Root motion from montages does not get mirrored correctly
UE - Characters - Animation - 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 ...
Unexpected corrections when sliding against other characters
UE - Gameplay - Player Movement - Oct 19, 2023We are seeing unexpected movement corrections sometimes when pushing one player character up against another character that isn't moving, or against other static primitives that have round features ...
ShouldMarkSyncPhases causes large pose discontinuities when sync leader changes
UE - Runtime - Anim BP - Aug 27, 2026The issue is caused by the way that we calculate the leader sample's Time vs the follower sample’s Time and how that calculation switches on the frame when a follower sample becomes a lead sample. ...
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 - Runtime - Character - 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 ...
Conflict between sequencer transform track and Parent Constraint from the Animation Mode breaks temporary pivot translation on any actor
UE - CAPT - 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 - Rendering - 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 ...
Wrong WPO motion vectors due to Periodic World Space node
UE - Rendering - Graphics Features - May 13, 2026We've noticed smearing in grass due to wrong motion vectors. This appears to be caused by lack of previous frame support in the periodic world space node. This is how we fixed it: In MaterialTempl ...
Virtual Memory leak when using specific rendering settings in the template project
UE - Rendering - Architecture - RHI - 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 ...
Niagara Mesh Renderer registers NumParticles x NumMeshVariants TLAS instances
UE - Rendering - Graphics Features - Ray Tracing - May 28, 2026When using the Niagara Mesh Renderer with multiple mesh variants selected via MeshIndex, the number of TLAS instances allocated is NumParticles × NumMeshVariants and enabling the Path Tracer can ca ...
UCharacterMovementComponent::CapsuleTouched crashes on UGeometryCollectionComponent overlap (unchecked USkinnedMeshComponent cast)
UE - Runtime - Character - Aug 21, 2026Summary: Confirmed that this exists in latest as well as 5.8 which is the origin or both tickets. This is a regression from 5.7 - although it looks like the guard was not aiming specifically to catch ...