STreeView won't show children below level 2

Hello,

Similar to this question Why do STreeView sub-nodes not expand? - UI - Unreal Engine Forums
My STreeView widget won’t expand when I click on a parent that’s below the root level.

My code

void SDialogTreeWidget::Construct(const FArguments& Args)
{
	
	Items.Add(MakeShareable(new FString("String1")));

	Items2.Add(MakeShareable(new FString("String6")));
	Items2.Add(MakeShareable(new FString("String7")));

	TreeViewWidget = SNew(STreeView<TSharedPtr<FString>>)
		.ItemHeight(48)
		.TreeItemsSource(&Items)
		.OnGenerateRow(this, &SDialogTreeWidget::OnGenerateRowForList)
		.OnGetChildren(this, &SDialogTreeWidget::GetChildren01);

	ChildSlot
		[
			SNew(SVerticalBox)
			+ SVerticalBox::Slot()
		[
			TreeViewWidget.ToSharedRef()
		]
		];
}

TSharedRef<ITableRow> SDialogTreeWidget::OnGenerateRowForList(TSharedPtr<FString> Item, const TSharedRef<STableViewBase>& OwnerTable)
{
	return
		SNew(STableRow<TSharedPtr<FString>>, OwnerTable)
		.Padding(2.0f)
		[
			SNew(STextBlock)
			.Text(FText::FromString(*Item))
		];
}

void SDialogTreeWidget::GetChildren01(TSharedPtr<FString> Item, TArray<TSharedPtr<FString>>& OutChildren)
{
	if (*Item == "String1")
	{
		OutChildren.Add(MakeShareable(new FString("String2")));
		OutChildren.Add(MakeShareable(new FString("String3")));
		OutChildren.Add(MakeShareable(new FString("String4")));
		OutChildren.Add(MakeShareable(new FString("String5")));
	}
	else if (*Item == "String3")
	{
		OutChildren.Append(Items2);
	}
}

245362-capture.png

Widget looks like this. Clicking on the arrow or double clicking won’t expand String3

Have you solved it? Because I have the same problem

No, I wasn’t able to resolve this. Ended up programming my own tree view