Attempting to set a new PIE window to Windowed Fullscreen mode causes both the new PIE window and the original Editor window to freeze and stop accepting input

UE - Platform - Apple - Dec 24, 2018

When starting PIE in a New Editor Window on a Mac, the both the new window and original Editor window will freeze and stop responding to inputs if an attempt is made to change the window to Windowed ...

OSS Steam: SteamSocket listen connections do not work after poll group changes

UE - Online - Oct 25, 2021

In 4.27 the logic in SteamSocket.cpp which is part of the SteamSockets plugin was changed to use Poll Groups instead of a removed API function that checked all children of a listen socket. However,  ...

Switchboard Unable to Launch Multi-User Slate Server in Launcher Builds

zComponent - Archive - Jan 14, 2023

Switchboard is unable to launch the Multi-User Slate Server in launcher builds.  This is because the default install location has "Program Files and "Epic Games" in the path (aka folders with spaces ...

Disabling Grid ShowFlag also hides billboard sprites and volume outlines

UE - Rendering - Features - Nov 8, 2023

The following odd behavior did not happen until UE 5.2, but happens in the latest UE 5.3. When the "Grid" show flag is disabled in the Level Editor Viewport, all billboard sprites and volume outlin ...

Animation attributes - user defined structs containing types defined in plugins cannot be registered

UE - Runtime - Animation - Dec 18, 2023

This issue is caused by us forcing user defined structs to be loaded as part of AttributeTypes::Initialize.  That is called after at the ObjectSystemReady run phase during engine initialization howe ...

Packed Level Actors will create ISMs with inverted normals when a portion of static meshes have negative scales. This is apparent with two-sided materials.

UE - Engine Scaling - Streaming - Feb 17, 2025

Packed level actors will create ISM instances with inverted normals when the selection of meshes used to create the packed level actor contains a subset of meshes with negative scales. This is the ...

MRQ GBuffer Output Renders Normal GBuffer instead of BaseColor

UE - CAPT - Color Pipeline and Rendering - MRQ - Feb 27, 2025

When attempting to use console variables to render the BaseColor output, the GBuffer overview or GBuffer normal output is rendered instead.  Using the commands in the Editor viewport shows the BaseC ...

In 5.7, a Sequencer that contains a Spawnable ChaosCacheManager will crash the Engine on EndPlay

UE - Runtime - Simulation - Nov 30, 2025

In 5.7, a Sequencer that contains a Spawnable ChaosCacheManager will crash the Engine on EndPlay. The licensee has reported, and I've confirmed, that this behavior started in 5.7. I've confirmed thi ...

Hierarchical and normal Instanced Static Mesh Components do not maintain PerInstanceRandom values when transforms are modified

UE - Graphics Features - Nov 6, 2017

When using PerInstanceRandom in a material that is applied to a Hierarchical or normal Instanced Static Mesh component, there are issues of the value resetting when certain transform operations are ...

Duplicating Level With Large _BuiltData File Results in Editor Crash

UE - Foundation - Core - Jun 7, 2018

Trying to duplicate a level in the editor that has a large _BuiltData file results in a crash. In the case of the supplied test level, it is over 3 GB. Crash repros in 4.19.2 and Main (CL 4115885). ...