Child Actor Component Actor Duplicates and Persists After Play

UE - Gameplay - Sep 26, 2019

When an actor spawns another actor using AddChildActorComponent that comes alphabetically before it based on blueprint name it will spawn an extra actor that will persist when the scene is stopped d ...

Motion vectors not generating correctly in build

UE - Simulation - Physics - Nov 3, 2023

Also tried using “show VisualizeTemporalUpscaler” and noticed the frames that have missing motion vector data showed up as pops in the “show VisualizeReprojection” part of the visualizer. ...

Using "Change Class" on Spawnables, Possessable references retain old Class info

UE - Anim - Sequencer - Apr 22, 2024

Changing Class for Spawnable objects in Level Sequence did not have any impact on Possesable objects in Subsequence. It's still referencing the previous Class. Also found in Release-5.4, CL: 329753 ...

When importing static mesh using interchange and collision is generated, the asset does not have Collision Generated set to true

UE - Editor - Content Pipeline - Import and Export - May 19, 2025

Context: The Interchange Framework is Unreal Engine's import and export framework. When importing a mesh without collision, collision can be auto-generated. Problem: The problem is when importing s ...

Water tiles flicker in and out of visibility with instanced stereo enabled.

UE - Graphics Features - Jun 16, 2025

Water tiles flicker in and out of visibility when playing in VR with instanced stereo enabled. Requires instanced stereo rendering to be enabled (does not require forward shading to be enabled) Must ...

Actors re-scale to original size when attached to other actors

UE - Gameplay - Nov 21, 2014

Actors rescale to their original size when placed in level then attached to another actor. ...

If PIE is paused using the 'Pause key', the Pause or Resume buttons on the toolbar will no longer start PIE

Tools - Feb 5, 2015

If PIE is paused using the 'Pause key', the Pause or Resume buttons on the toolbar will no longer start PIE. You have to make sure that the icon is toggled to Pause, select the viewport, and then p ...

Changing code based component category causes component to become ineditable in blueprints

UE - Gameplay - Blueprint - Mar 27, 2015

When a component written in code has it's category setting changed in blueprint the rest of the details for that component will not be editable once the component is deselected and reselected. ...

[CrashReport] Assertion failed: OLEReferenceCount == 0 in UE4Editor_SlateRHIRenderer!FSlateRHIRenderer::DrawWindows_Private()

UE - Editor - UI Systems - Slate - Aug 22, 2017

This is a regular and longstanding crash in 4.17 that has occurred since at least 4.14. Users have not provided any descriptions of their actions when the crash occurred. There has been some previo ...

iOS Show External Login UI Blueprint Node fails on new iOS devices

UE - Online - Jun 6, 2019

I have been trying to test iOS online subsystem functionality for my game and thought that this blueprint node was just broken. This bug will probably catch many UE4 developers that are new to iOS b ...