Translucent materials in the PostMotionBlur pass can cause a flickering viewport artefact when using TAA

UE - Graphics Features - Feb 5, 2025

There 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 ...

Distance Field AO from Moveable Skylight (non-Lumen) invalidates AO incorrectly with a screenspace offset to the right of moving objects

UE - Graphics Features - Mar 25, 2025

When Global Illumination is set to “None” in the project settings the ambient occlusion does not correctly render shadows for moving objects. This has been observed in versions 5.4 and above. ...

WidgetComponent is not updated with occlusion culling disabled

UE - Platform - XR - May 7, 2025

LastRenderTime is never updated with occlusion culling disabled, so the widget component will always stop updating.  (see UWidgetComponent::ShouldDrawWidget) Developers can force updates by TickWhen ...

Static lights become stationary after toggling visiblity of level in packaged build

UE - Graphics Features - Jun 11, 2025

In 5.5, there is a regression with baked lighting where static lights become stationary lights when a level is hidden and then made visible again. This happens in packaged builds and shows up as sta ...

SAnalogSlider moves slowly when step size is large

UE - Editor - UI Systems - Slate - Mar 6, 2024

SAnalogSlider calculates FastestStepTime by multiplying the step size value by a constant, resulting in high numbers for larger step sizes. This gets lerped from 1 and used as the repeat time, resul ...

Join in progress clients won't receive that a net startup actor is hidden

UE - Networking - Jun 21, 2024

This seems to be because IsNetRelevantFor checks if the actor is hidden, resulting in a hidden actor not being considered relevant to clients. However, if it is a net startup actor, this will result ...

FDateRange cannot be declared as UPROPERTY

UE - CoreTech - UObject - Sep 4, 2024

Unlike other range wrapper structs, such as FFloatRange, marking a FDateRange as a UPROPERTY results in the following error: error : Unable to find 'class', 'delegate', 'enum', or 'struct' with nam ...

Lumen ignores Landscape Holes (Landscape Visibility) when Hardware Ray Tracing is enabled and Ray Lighting Mode is set to Surface Cache

UE - Graphics Features - Ray Tracing - Jan 31, 2025

Context Lumen is the default global illumination and reflections system. Lumen renders diffuse interreflection with infinite bounces and indirect specular reflections in large, detailed environments ...

Skylighting on distant objects causes severe flickering with Lumen

UE - Graphics Features - Lumen - Mar 31, 2025

Lighting on distant meshes flickers when using Lumen and Skylights. Turning Lumen off and lighting from the skylight is stable. Turning off Lumen screen traces also lowers the amount of flickering ...