Unreal Engine Issues and Bug Tracker (UE-138124)

Description

Created a new level and added a terrain. Added grass foliage and enabled density scaling located in the grass foliage settings mode. After placing foliage on terrain, the editor crashes.

This is not occurring in 5.0 Release only in early access. This is a regression, it is not occurring in 4.27.

Steps to Reproduce

Create a new project.
Create a new map.
Create a terrain.
In foliage mode, add a grass mesh.
Select the newly added grass mesh in foliage mode.
In the settings, enable density scaling.
Start placing grass onto the terrain.

Result: The editor will crash.

Expected Result: Foliage can be placed without the editor crashing.

Callstack

LoginId:97ae523f4b2570765960659737b45e3f
EpicAccountId:be8b4100f7e24317a91b10eb1a9d8676

Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers/Array.h] [Line: 707] Array index out of bounds: -1 from an array of size 480

UnrealEditor_Engine!FInstancedStaticMeshSceneProxy::SetupProxy() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\InstancedStaticMesh.cpp:1106]
UnrealEditor_Engine!FHierarchicalStaticMeshSceneProxy::FHierarchicalStaticMeshSceneProxy() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\HierarchicalInstancedStaticMesh.cpp:882]
UnrealEditor_Engine!UHierarchicalInstancedStaticMeshComponent::CreateSceneProxy() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\HierarchicalInstancedStaticMesh.cpp:3186]
UnrealEditor_Renderer!FScene::AddPrimitive() [D:\build\++UE5\Sync\Engine\Source\Runtime\Renderer\Private\RendererScene.cpp:1202]
UnrealEditor_Engine!UPrimitiveComponent::CreateRenderState_Concurrent() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Components\PrimitiveComponent.cpp:581]
UnrealEditor_Engine!UStaticMeshComponent::CreateRenderState_Concurrent() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Components\StaticMeshComponent.cpp:697]
UnrealEditor_Engine!UActorComponent::RecreateRenderState_Concurrent() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Components\ActorComponent.cpp:1637]
UnrealEditor_Engine!UActorComponent::DoDeferredRenderUpdates_Concurrent() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Components\ActorComponent.cpp:1710]
UnrealEditor_Engine!<lambda_d76a63ca40e19d7af8a407ce7f4093d3>::operator()() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\LevelTick.cpp:1171]
UnrealEditor_Engine!UWorld::SendAllEndOfFrameUpdates() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\LevelTick.cpp:1202]
UnrealEditor_Renderer!FRendererModule::BeginRenderingViewFamily() [D:\build\++UE5\Sync\Engine\Source\Runtime\Renderer\Private\SceneRendering.cpp:3842]
UnrealEditor_UnrealEd!FEditorViewportClient::Draw() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorViewportClient.cpp:3986]
UnrealEditor_Engine!FViewport::Draw() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\UnrealClient.cpp:1564]
UnrealEditor_UnrealEd!UEditorEngine::UpdateSingleViewportClient() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorEngine.cpp:2172]
UnrealEditor_UnrealEd!UEditorEngine::Tick() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorEngine.cpp:1867]
UnrealEditor_UnrealEd!UUnrealEdEngine::Tick() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\UnrealEdEngine.cpp:450]
UnrealEditor!FEngineLoop::Tick() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:5032]
UnrealEditor!GuardedMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:171]
UnrealEditor!GuardedMainWrapper() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:137]
UnrealEditor!WinMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:268]
UnrealEditor!__scrt_common_main_seh() [d:\agent\_work\5\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
kernel32
ntdll

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Won't Fix

Component	UE - World Creation - Worldbuilding Tools - Foliage
Affects Versions	5.0-early access

Created	Jan 3, 2022
Resolved	Jan 3, 2022
Updated	Mar 25, 2022

View Jira Issue

UE-138124

Editor crashing with density scaling is enabled on foliage being placed on a terrain.

Editor crashing with density scaling is enabled on foliage being placed on a terrain.

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