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 ...

Unable to save a map file when editing a LevelInstance by placing multiple LevelInstances on a PersistentLevel

UE - World Creation - Worldbuilding Tools - Level Instances - Mar 17, 2023

Can not save the map file, if trying to edit a LevelInstance in a PersistentLevel where multiple LevelInstances are placed. The workaround is to open and edit the LevelInstance as PersistentLevel.  ...

Lumen indirect lighting artifacts when far from world origin

UE - Graphics Features - Lumen - Feb 6, 2024

Lumen seems to not be using Large World Coordinates somewhere. The Lumen Scene develops artifacts at large distances (5000 KM) from the world origin. ...

Mobile Preview - Custom Stencil 4.23 Regression

UE - Platform - Mobile - Oct 25, 2019

Regression when using custom stencil with in-editor mobile preview. This does NOT reproduce in MAIN at CL 9730599 ...

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. ...

When running multiple clients in PIE the second player's inputs become toggled every tick when setting Input mode Game only on tick

UE - Editor - UI Systems - Slate - Jul 9, 2015

A user has found that setting input mode to game only on tick will cause the client in PIE to toggle their inputs on and off every tick. If this test is run with a single player the inputs are const ...

Screen Space Widget Component offset in Editor Viewport when using Windows Scaling

UE - Editor - UI Systems - Jul 23, 2018

Using Windows scaling above 100% now causes Screen Space 3D Widgets to be offset. (Pressing F11 for fullscreen or launching will cause widget to appear in correct location) ...

Malformed command sent to UAT if BuildCookRun command ends with a trailing slash ("\")

UE - Foundation - Cpp Tools - Feb 14, 2019

Including a trailing slash ("\") at the end of a BuildCookRun command sent to UAT results in UAT receiving a malformed command. If the command ends with a slash, the resulting command that UAT recei ...

The Find Node Can Crash on Compile After a Blueprint Compile Error

UE - Gameplay - Nov 21, 2019

The "Find" node can cause a crash if the a map with a struct value changes type while connected, is disconnected and reconnected. Compilation fails and crashes the engine. Found in 4.23.1 CL#963142 ...

first struct variable not shown by Intelisense

UE - Foundation - Core - Feb 18, 2015

When invoking a custom struct, the first listed variable will not appear in the Intelisense window. ...