UV Offset Effect Material in RetainerBox Causes Visual Artifacts in Editor Preview

UE - Editor - UI Systems - UMG - Apr 22, 2025

When a UV Offset is applied in a RetainerBox effect material, visual artifacts appear only in the editor — not at runtime — if a widget with a dotted preview outline (like CanvasPanel) is placed dir ...

Screen Space Widget Component offset in Editor Viewport when using Windows Scaling

UE - Editor - UI Systems - Jul 23, 2018

Using Windows scaling above 100% now causes Screen Space 3D Widgets to be offset. (Pressing F11 for fullscreen or launching will cause widget to appear in correct location) ...

Components defaults not updating on hot reload

UE - Gameplay - Blueprint - Apr 11, 2017

Certain values, when changed in code, are not updated in a hot reload. For example, changing the Target Arm Length of a spring arm component will updated after hot reload, but changing the Scale do ...

CPU Lightmass generates different lighting results on a landscape if executed via a commandlet vs through the editor

UE - Graphics Features - Jul 3, 2025

Building lighting via commandlet and via editor are giving different results. To prevent one method from polluting the other via Swarm cache, the cache needs to be cleared in between tests. ...

Navigation: Exiting game while async nav building tasks are running can cause null pointer access of OctreeController.NavOctree from worker thread

UE - AI - Navigation - Nov 1, 2024

Context Projects can turn on the project setting bDoFullyAsyncNavDataGathering to execute navigation mesh building tasks on worker threads. Some of these tasks will access the NavOctree, whose life ...

Navigation: Exiting game while async nav building tasks are running can cause null pointer access of OctreeController.NavOctree from worker thread

UE - AI - Navigation - Jan 14, 2025

Context Projects can turn on the project setting bDoFullyAsyncNavDataGathering to execute navigation mesh building tasks on worker threads. Some of these tasks will access the NavOctree, whose life ...

FileSystemDerivedDataBackend may output a corrupted access log

UE - Foundation - Core - Derived Data - May 20, 2021

This problem is caused by the AccessLogWriter has not been flushed at the termination. The following workaround flushes the Writer.class FFileSystemDerivedDataBackend : public FDerivedDataBackendInt ...

Hot reload can prevent code components from being accessible in blueprints

UE - Foundation - Cpp Tools - Hot Reload - Sep 29, 2017

When a class is edited / hot reload preformed, code based components are sometimes removed from the MyBlueprint > Variables section and cannot be dragged from the Components tab into the graph with ...

GAS PlayMontageAndWait: Server applies root motion with wrong scale at last montage tick

UE - Gameplay - Gameplay Ability System - Apr 3, 2024

User reported: when playing an AnimMontage via GameplayAbility with the PlayMontageAndWait ability task that has a custom value for AnimRootMotionTranslationScale, (dedicated) servers can apply an i ...

Damping is handled differently at lower frame rates

UE - Gameplay - Aug 3, 2016

Damping is handled differently at lower frame rates. Slight changes in damping at lower FPS (25) drastically effects objects and isn't applied in the same way as at higher FPS (60) User Description ...