When a Niagara User Parameter is renamed, mesh bindings on Niagara Mesh Renderers are not updated, and the binding is silently broken

UE - Niagara - Mar 13, 2025

In Niagara, Mesh Renderers expose a "Meshes" array for selecting the meshes to be rendered. On each array entry, a property "Mesh Parameter Binding" is available and allows the user to override that ...

Mutable compile hangs indefinitely when using Customizable Object Extension Data Constants

UE - Anim - Mutable - Oct 25, 2025

I am getting a CO compile to hang indefinitely while compiling. It seems to be caused by the optimization in LocalLogicOptimiserAST that tries to convert 3+ conditionals into a switch statement. It ...

Occlusion Queries for Static Meshes with ERuntimeVirtualTextureMainPassType::Exclusive

UE - Rendering - Architecture - Feb 20, 2026

Static Meshes that draw into RVTs and have "Draw In Main Pass" is set to "From Virtual Texture" (ERuntimeVirtualTextureMainPassType::Exclusive) will still draw in Occlusion Queries. This can be tr ...

When Building Light for a SubLevel of a project, BSPs will be built into the level regardless if hidden or not

UE - LD & Modeling - Modeling Tools - BSP - Feb 23, 2016

BSPs will be built with light/shadow extrapolated even if they are placed in a hidden sub_level of the project at the time of building. Also Tested in 4.10.4, 4.11 Preview 6 and Dev-Editor-CL-28772 ...

Input pins of BP node are not updated after a hot reload

UE - Gameplay - Blueprint - Apr 17, 2015

If a code defined function that takes in a parameter is called from blueprints, the BP node will show the input pin for the parameter. If the parameter list is changed after the node is created and ...

Construction script on child actor components not respected in PIE

UE - Gameplay - Blueprint - Jan 14, 2016

Child Actor Components run their construction scripts upon parent's placement in level. However, these specifications are not maintained once PIE is initiated. ...

Child blueprint loses categories after parent is compiled and PIE

UE - Gameplay - Blueprint - Jul 30, 2015

If a parent blueprint is compiled and then play in editor is utilized. The child blueprint will lose categories in it's my detail's pane until recompiled. Note: Licensee reports that variables res ...

The Spawn Actor from Class node outputs an Actor reference when a Select node is attached to the Class input, even if both options are of the same child type

UE - Gameplay - Blueprint - Jun 18, 2015

The Spawn Actor from Class node outputs an Actor reference when a Select node is attached to the Class input, even if both options are of the same child type. For example, if two Characters are the ...

Start up movies will only play for a second or two and then the level will load.

UE - Platform - Mobile - Oct 27, 2014

If you place a mp4 file into the startup movies section of the Project Settings, the movie will only play for a brief time before the level loads. If you play the play the level with the startup m ...

Creating a Blueprint out of existing Blueprints removes all assigned Static Meshes from components

UE - Gameplay - Blueprint - Aug 11, 2015

Creating a Blueprint out of existing Blueprints removes all assigned Static Meshes from components. Reproduced in 4.8.3 binary, 4.9 Releases (//depot/UE4-Releases/4.9/Promotable-CL-2650750), and Ma ...