UClass::SparseClassDataStruct null at editor-time for child blueprints until compile

UE - Framework - Blueprint - May 29, 2024

Child blueprints of a blueprint of a native actor class with sparse data can have an incorrectly null SparseClassDataStruct value, and thus fail to initialzie their SparseClassData. This affects edi ...

Editor crashes when right clicking a box collision after adding a converted static mesh in blueprint editor

UE - Gameplay - Blueprint - Sep 1, 2016

I created a cylinder with a subtractive cylinder inside of it. I also used a box BSP with a subtractive box inside of it and got the crash to repro. I tried with a sphere BSP twice and didn't get ...

Assertion failed on attempt to reload edited Dataprep asset

UE - Editor - Content Pipeline - Visual Dataprep - Feb 28, 2022

Editor crashes after user tries to reload Dataprep asset after editing Filter By Actor label card in QAEnterprise project. Regression - Yes(Priority Critical), wasn't able to repro this issue in // ...

Thirdperson Character not Replicating correctly after being attached to an Actor

UE - Networking - Dec 20, 2017

Problem description: When the Third Person Character gets attached to any other Actor (AttachToActor, Rule: Keep World), from the view of other clients the character (capsule, skeletal mesh) is out ...

.ini files for packaged games have their settings wiped clean every time the game is run.

The settings .ini files for games packaged for windows appear to be getting overwritten with blank files whenever the game is run. Even if settings are added to the .ini files manually, the files be ...

Combining Layered Blend Per Bone with Cached Pose nodes can break root motion extraction

UE - Anim - Gameplay - Aug 23, 2023

When the input to a Layered Blend Per Bone node is two instances of the same cached pose, we aren't sampling root motion correctly.  In the attached example, the weight on the root bone is 0 and Ble ...

"Enable Stencil Test" Mobile crash

UE - Graphics Features - Sep 10, 2019

A material with 'enable stencil test' will crash on mobile. Enable Stencil Test is a new option in materials as of 4.23 Confirmed with OpenGL 3.1 + 2 and Vulkan on Pixel XL Also Crashes on iOS ...

Scene Color node with UV input on a transparent material renders incorrectly in stereo

UE - Platform - XR - Jan 19, 2021

From Licensee: When we have Instanced Stereo enabled, all our materials that use Scene expression nodes (SceneDepth, SceneColor, etc...), render incorrectly in the right eye. It only happens to the ...

Deadlock in UAnimationSequencerDataModel::Evaluate where FScopeLock Lock(&EvaluationLock) blocks execution indefinitely

UE - Anim - Nov 4, 2025

When both the Sequencer Editor and an Animation Curve Editor are open for the same animation asset, the editor freezes completely upon editing the curve. Analysis indicates that the freeze is caus ...

Possible incorrect pointer manipulation in BeginPackageCacheForCookedPlatformData

UE - Foundation - Core - Cooker - Dec 12, 2017

In UCookOnTheFlyServer::BeginPackageCacheForCookedPlatformData(), there is a pointer to int32 called CurrentAsyncCache that is used as an index. It's value is dereferenced before it is checked, but ...