In -game in Editor, if streaming-in a LevelInstance and initialize its world partition, then leaving that cell and make it go outside the streaming grid, to re-enter it again, will trigger a check(!StreamingPolicy) if no GC has happened during that time.

UE - World Creation - Worldbuilding Tools - World Partition - Jan 27, 2025

This crash can be fixed by adding a couple of || IsRunningGame() like it is done here:    FGenerateStreamingContext Context = FGenerateStreamingContext()        .SetLevelPackagesToGenerate((bIsPIE ...

Moving a Widget in UMG by dragging the position value results in Stuttering and Jerking

UE - Editor - UI Systems - UMG - Aug 8, 2022

This is a regression. Tested in //UE4/Release-4.27 CL#18319896 Moving widgets within UMG by dragging the position value with any sort of speed results in the widget stuttering and jerking around.  ...

MediaFramework movies not playing properly in Shipping

Media Framework - Nov 7, 2017

`check(Samples.Pop());` this kind of `Pop()` inside of a `check()` is in a few places in MediaSampleQueue.h and MediaSamples.cpp but `check()` expands to nothing in Shipping/Test, so, required work ...

Suspension CoM calculations don't update with mass.

UE - Simulation - Physics - Dec 15, 2016

UWheeledVehicleComponent calculates the Suspension settings only when the physics state is first created. When CoM is set through the editor, the vehicle is constructed with the appropriate offset ...

Using multiple SceneCapture2D with DLSS Enabled crashes UE

UE - Graphics Features - Nov 22, 2024

A licensee is reporting a crash (or rather a check fail) in Sceneview.cpp which happens with when a SceneCapture2D is used with DLSS enabled. He has a fix, and wants to share it with us for integrat ...

Material Layers "swap" location instead of shift downwards.

UE - Rendering Architecture - Materials - Oct 17, 2023

Licensee request for this as it is affecting productivity. Likely requires a method of allowing a user to choose which behaviour they prefer. For reference, the behaviour changed in CL 11684461 to f ...

UObjects returned from "Get Item Children" in a TreeView widget causes an engine crash, due to invalid pointers

UE - CoreTech - UObject - Jun 9, 2020

UObjects returned from "Get Item Children" in a TreeView widget causes an engine crash, due to invalid pointers. User has proposed the following fix: The best fix is probably such: When Slate list ...

Instance overlap functions for Foliage Instanced Static Meshes detects instances inconsistently

UE - World Creation - Worldbuilding Tools - Foliage - Apr 14, 2022

Instance overlap functions for Foliage Instanced Static Meshes detects instances incorrectly. I was able to see this occur with both the Sphere and Box functions. In addition, I drew out debug sphe ...

Crash when using StaticDuplicateObject with mismathced Source and Destination class types

UE - Foundation - Jun 19, 2025

Starting in Unreal Engine 5.4, StaticDuplicateObject internally switched to using Unversioned Property Serialization (UPS) for performance reasons. However, UPS assumes the source and destination ob ...

Static mesh's material slot's cast shadow does not require a build of StaticLight

UE - Graphics Features - Dec 7, 2017

If static mesh's material slot's cast shadow is changed, UE4 does not show "LIGHTING NEEDS TO BE REBUILT". I solved it with the following fixes. StaticMeshEditorTools.cpp void FMeshSectionSettin ...