Unreal Engine Issues
Unreal Engine Issues
ShouldMarkSyncPhases causes 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. ...
Ambient occlusion causing ghosting for animations when viewport is resized on DX11
UE - Rendering - 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 - 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 - ACT Character - 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 - 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 - 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 - 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 - 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 ...
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 - Core - Systems - 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 ...