Open Formats: Interchange Import PIE - Importing static mesh while a PIE session is running permanently breaks nanite on the asset

UE - Editor - Open File Formats - Mar 12, 2025

Importing a Static Mesh during PIE can cause it to never enable Nanite, even if it reports that Nanite is enabled. To re-enable Nanite on the mesh, the asset needs to be deleted and imported again ...

World-locked stereo layers for SteamVR are not positioned correctly

UE - Platform - XR - Nov 14, 2017

World-locked stereo layers don't seem to be in the correct place when viewed in SteamVR. In 4.16, if you Subtracted the difference of VR origin location and world origin location and offset the pos ...

ISM + WPO = broken motion vectors?

UE - Graphics Features - Nov 5, 2024

Instanced Static Meshes will have incorrect velocity if a Material uses World Position Offset. Fixed WPO in a material causes significant velocity on the ISM. This was also replicated in //UE5/Rele ...

[CrashReport] Crash in UE4Editor_AudioEditor!`FSoundSubmixGraphSchemaAction

UE - Anim - Sequencer - Jun 22, 2017

This is a common crash occurring in the 4.16 release. This is potentially a continuation of [Link Removed], which was closed out when it received additional logging in 4.16. A log file is attached. ...

Displaying Revision control history for a file ending in an "undo" of a revision can cause a crash

UE - Editor - Jun 18, 2024

This crash is caused by how source control history is managed and shown. In this specific case the source control software is Perforce. As written in the repro steps, it can happen to any uasset tha ...

Ensure triggered in FBoundsCacheElement::GetValue when adding ISM instances in Construction Script

UE - AI - Oct 8, 2025

An ensure is triggered in FBoundsCacheElement::GetValue when adding instances to an InstancedStaticMeshComponent inside a Blueprint’s Construction Script. This occurs when the ISM component is navig ...

[CrashReport] UE4Editor_BlueprintGraph!BlueprintActionFilterImpl::IsEventUnimplementable() [blueprintactionfilter.cpp:588]

UE - Gameplay - Blueprint - Jun 1, 2016

This crash has been reported through the 4.12 Previews and is continuing to occur in the 4.12.0 release. Additional information about this crash is not available at this time, however it may be the ...

ModularGameplay and other runtime plugins have wrong LoadingPhase

UE - Gameplay - Jun 30, 2022

Plugins that provide blueprint-accessible libraries generally need to be set the PreDefault LoadingPhase so they can be properly loaded before game-specific data that loads early in the Default load ...

UV Flipping Mode Causes Stretching of Particles

UE - Niagara - Nov 17, 2017

If "UVFlipping Mode" under Rendering on the Required node of an emitter is set to anything other than "None," the particles can become stretched and distorted. As a workaround, I have discovered th ...

Crash When Assigning a Static Mesh to the "Sample Static Mesh" Module

UE - Niagara - Jun 28, 2018

When assigning a static mesh to the "Sample Static Mesh" module, the engine will crash as soon as you select a mesh and click "Fix Now". If the mesh already has CPU access enabled it will crash as s ...