Deleting the code files for a custom component from a project will result in an Engine crash when trying to open any Blueprint using that component.

UE - Gameplay - Blueprint - Feb 20, 2015

Adding a custom component to a Blueprint and then deleting the code class defining that custom component from the project will crash the Editor any time you try to open a Blueprint containing that c ...

ARCore Non-AR Camera inherits AR Camera rotation

UE - Platform - XR - Jul 25, 2018

When transitioning from AR map/pawn to Non-AR map/pawn the direction the phone is facing is applied to Non-AR pawn. Only occurring on Android/ARCore Also tested in Main CL #4229747 Tested with Pi ...

Hot Reload fails if a project and Engine are placed next to each other in the same root folder that has the same name as the project

UE - Foundation - Cpp Tools - Hot Reload - Jan 8, 2019

Hot Reload does not work if a project and the Engine that project is associated with are placed next to each other in the same root folder that shares the same name as the project. During the Hot Re ...

Previous Tangent Recalc` and Size by Life misbehave at low FPS

UE - Niagara - Jun 18, 2019

At low FPS particle systems with "Previous Tangent Recalculation" enabled in the Ribbon Data result in messy mesh generation. Found in 4.21 CL# 4753647, 4.22 CL# 6574378, 4.23 CL# 6925347, and 4.24 ...

Skybox not rendering in packaged project with Vertex Fogging enabled

UE - Platform - XR - Feb 10, 2020

Vertex Fogging setting causes skybox material on large skybox mesh to not be rendered. Confirmation for 4.25 blocked by [Link Removed] ...

Actor attached to child actor fails to serialize as part of map

UE - Framework - Components - Nov 3, 2023

Attaching other actors to a child actor (actor spawned by ChildActorComponent) fails to serialize correctly as part of the map. The attached actor loads as detached and resets its position back to w ...

TUnion copy constructor causes the editor to assert due to Unrecognized TUnion subtype

UE - Foundation - Core - Mar 15, 2016

The TUnion copy constructor causes the editor to toss an assert due to it claiming that the passed in TUnion is of an Unrecognized TUnion subtype. ...

BP child not overriding parent's mesh in Nativized builds

UE - Gameplay - Blueprint Runtime - Jan 3, 2017

The mesh on the right is a child of the one on the left, in a non-nativized cooked build it's a sphere, but in a nativized one, it's a cube. Regression: Working: UE4/Main, 4.15 CL 3233043 Broken: U ...

Debug values not updated for parallel eval Animation BPs

OLD - Anim - Oct 22, 2019

The watched values of a level instanced ABP do not update if a.ParallelAnimEvaluation is enabled. ...

Editor vs Runtime: Inconsistent data layer behavior when attaching actors

UE - World Creation - Worldbuilding Tools - World Partition - Jun 5, 2025

In editor, data layer system respects the data layer settings for each actor, but at runtime, the condition check is made collectively for each actor cluster, resulting in differences in behavior. ...