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. ...

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. ...

Unable to create a 'World Soft Object Reference' Variable from the Variables Panel

UE - Framework - Blueprint Editor - Jun 21, 2018

Soft references to World objects (TSoftObjectPtr<UWorld>) cannot be directly created in blueprints. These types work fine in blueprints but cannot be directly created. The reason soft references are ...

Strange intermittent CCD behavior on constrained physics bodies

UE - Simulation - Physics - Oct 23, 2019

There is some strange issue with CCD where constrained CCD objects can get velocity nulled when hitting things while constrained, its very hard to reproduce normally in engine but happens often in V ...

GAS and single process PIE: modifiable static variables accessed by server and client

UE - Gameplay - Gameplay Ability System - Nov 16, 2022

See: UAbilitySystemGlobals::HandlePreLoadMap GAS features static variables that are modified by both server and client, thus result in issues in single process PIE where they access the same memory ...