Lighting channels not working as expected when enabling Ray Tracing Shadow

UE - Graphics Features - Lumen - Oct 13, 2020

Non-Ray Tracing Shadows are only cast from lights on meshes assigned to the same Lighting Channel. When enabling Ray Tracing Shadows this is not the case. Lights will still cast Ray Tracing Shadows ...

[Spatialization] - When a sound starts playing while the listener in in the Binaural Radius, when they exit the sound stops playing

UE - Audio - Spatialization - Nov 18, 2021

If a sound starts playing while the listener is inside the binarual radius, the sound stops abruptly when they leave the radius. Does not occur if the listener starts in the binaural radius. Does no ...

Integrity of AnimSyncMarkers compromised while playing AnimMontage with root motion in server side

UE - Anim - Gameplay - Jan 11, 2023

Reference UDN as it explains well the cause of the issue. ...

[MetaSounds] - If the audio output hits an extreme Gain value, the Audio Meter Widget stops responding

UE - Audio - MetaSounds - May 20, 2022

It's possible to have the Audio Meter widget stop responding if you set the Gain really high. It will cease to work as long as the MetaSound window is open. Closing and reopening the MetaSound windo ...

Material Layers Ignore Virtual Texture Sampler Restrictions

UE - Rendering Architecture - Mar 25, 2024

Virtual Textures can be assigned to Texture Sample Parameters that are not configured for Virtual Textures, if that parameter is inside of a Material Layer. Also found in Release-5.4, CL 32426910 ...

Translucency area has stripe-style issue on TSR

UE - Graphics Features - Mar 28, 2024

The TSR History Rejection buffer develops a grid-like artifact over translucent, camera-facingplanes. This problem can be mitigated by increasing r.TSR.ShadingRejection.TileOverscan from 3 to 4 with ...

WasRecentlyRendered() and GetLastRenderTimeOnScreen() still triggers when a skeletal mesh re-enters the view frustum despite being occluded.

UE - Rendering Architecture - Dec 4, 2024

AActor::WasRecentlyRendered() and UPrimitiveComponent::GetLastRenderTimeOnScreen() both still trigger when a skeletal mesh (occluded behind a wall) re-enters the player's view frustum after being ou ...

When a Niagara User Parameter is renamed, mesh bindings on Niagara Mesh Renderers are not updated, and the binding is silently broken

UE - Niagara - Mar 13, 2025

In Niagara, Mesh Renderers expose a "Meshes" array for selecting the meshes to be rendered. On each array entry, a property "Mesh Parameter Binding" is available and allows the user to override that ...

Mutable compile hangs indefinitely when using Customizable Object Extension Data Constants

UE - Anim - Mutable - Oct 25, 2025

I am getting a CO compile to hang indefinitely while compiling. It seems to be caused by the optimization in LocalLogicOptimiserAST that tries to convert 3+ conditionals into a switch statement. It ...

Input pins of BP node are not updated after a hot reload

UE - Gameplay - Blueprint - Apr 17, 2015

If a code defined function that takes in a parameter is called from blueprints, the BP node will show the input pin for the parameter. If the parameter list is changed after the node is created and ...