Blueprint based on custom Vehicle class can't be edited after closing/opening the editor

UE - Gameplay - Blueprint - Sep 8, 2015

If a custom class named Vehicle is used as the base of a blueprint, closing and reopening the editor prevents the blueprint from being opened. The editor reports that the derived class is invalid. ...

Attempting to Open a Widget Blueprint With Animation and Timeline Panels Hidden Causes the Editor to Crash

UE - Editor - UI Systems - Nov 11, 2015

When you attempt to open a widget blueprint when you have hidden the animation and timeline panels, the editor will crash. There is a workaround: Window->Reset Layout will allow you to open the blu ...

Cannot Add Collision to an EQS Testing Pawn

UE - AI - Jan 6, 2016

Attempting to add collision to an EQSTestingPawn class is not possible, as the inherited capsule component seems to override any new collision. Simulating with the inherited capsule will cause the P ...

Cloth environment collisions with APEX clothing is not thread safe.

UE - Simulation - Physics - Character - Jan 17, 2017

This looks like a thread safety bug that's been in the clothing system for a very long time. Essentially a skeletal mesh component does a transform update and attempts to update the collisions of a ...

With "Use Default Sample Rate" disabled, animations with 24fps get resampled to 30fps

Tools - May 30, 2017

With "Use Default Sample Rate" disabled, animations under 30fps get resampled to 30fps ...

User project crashes after changing struct

UE - Gameplay - Blueprint - Aug 10, 2017

Sequencer 3D Trajectories run very slow on deep hierarchies

UE - Anim - Sequencer - Aug 27, 2018

Using a Level Sequence with deep hierarchies causes the FPS to drop to low numbers when they are all selected within the Sequence. This is a regression from 4.19.2 (CL-4033788). This issue was repo ...

Float value of AIDataProvider_QueryParams is cast faild

UE - AI - Oct 9, 2018

IntValue and BoolValue is always indefinite value in UAIDataProvider_QueryParams::BindData(). Attach the result of Watch in VS. ...

GenerateVisibileRayTracingMeshCommands Severely Reduces Foliage Performance Even if no RayTracing is Used

UE - Graphics Features - Lumen - Sep 18, 2019

GenerateVisibileRayTracingMeshCommands Severely Reduces Foliage Performance Even if no RayTracing is Used. Found in 4.23 CL# 8386587 and 4.24 CL# 8748719 ...

Landscape smooth and flatten tools deform the terrain incorrectly

UE - Graphics Tools - Terrain - Landscape - May 25, 2022

The Landscape smooth and flatten tools can deform the landscape incorrectly causing chunks of the landscape to be removed (see attached image). ...