TreeView Not Rendering Correctly

[CHIPSNetwork]

I'm following the docs as closely as possible. I fail to get the icon/character/symbol to the left of an unexpanded group.
What's the trick to getting this to appear?

My contentpage:

<ContentPage.ToolbarItems>
    <ToolbarItem Text="Add New"  />
</ContentPage.ToolbarItems>
<ContentPage.Content>
    <ScrollView>
        <StackLayout>
            <material:TreeView x:Name="treeView" ItemsSource="{Binding Nodes}" ChildrenBinding="{Binding Children}" SelectionMode="Single" HeightRequest="300" WidthRequest="300" >
               
            </material:TreeView> 
            <SearchBar x:Name="CustomerSearch"  Placeholder="Select Customer..." TextChanged="OnTextChanged" ></SearchBar>
            <ListView x:Name="searchResults"  HorizontalOptions="CenterAndExpand" ItemTapped="OnItemTapped" HeightRequest="500" MinimumHeightRequest="400" IsVisible="False">
                <ListView.ItemTemplate>

                    <DataTemplate>
                        <ViewCell>
                            <Grid>
                                <Label Grid.Column="0" Text="{Binding CustName}" />
                            </Grid>
                        </ViewCell>
                    </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>
        
        </StackLayout>
    </ScrollView>
</ContentPage.Content>

My Mauiprogram.cs:

[CHIPSNetwork]

My .cs file for the page:

using ChipsAppV3.Models;
using Microsoft.Maui.Controls;
using System.Collections.ObjectModel;

namespace ChipsAppV3;

public partial class NotesPage : ContentPage
{
int New_Customer_ID = 0;
public ObservableCollection Nodes { get; set; } = new();
public NotesPage()
{
AddNodes();
BindingContext = this;

    InitializeComponent();

    
}


void OnTextChanged(object sender, TextChangedEventArgs e)
{
    SearchBar searchBar = (SearchBar)sender;
    var results = GlobalStuff.GlobalCustomer_Brief_ViewModel.GetSearchResults(searchBar.Text);
    searchResults.ItemsSource = results;
    searchResults.IsVisible = true;
    if (e.NewTextValue == string.Empty || e.NewTextValue == null)
    {
        searchResults.IsVisible = false;
    }
}

public async void OnItemTapped(object o, ItemTappedEventArgs e)
{
    Customer_Brief_Item dataItem = (Customer_Brief_Item)e.Item;

    CustomerSearch.Text = "";
    CustomerSearch.Placeholder = dataItem.CustName;
    New_Customer_ID = dataItem.CustID;
    OnPropertyChanged(nameof(CustomerSearch.Placeholder));
    searchResults.IsVisible = false;
    await reload_notes();
}

async Task reload_notes()
{
}



  

    public void AddNodes()
    {
        Nodes.Add(new MyItem("A")
        {
            Children =
        {
            new MyItem("A.1"),
            new MyItem("A.2"),
        }
        });
        Nodes.Add(new MyItem("B")
        {
            Children =
        {
            new MyItem("B.1")
            {
                Children =
                {
                    new MyItem("B.1.a"),
                    new MyItem("B.1.b"),
                    new MyItem("B.1.c"),
                    new MyItem("B.1.d"),

                }
            },
            new MyItem("B.2"),
        }
        });
        Nodes.Add(new MyItem("C"));
        Nodes.Add(new MyItem("D"));
    }

public class MyItem
{
    
    public MyItem(string name) // For easy initialization (optional)
    {
        Name = name;
    }

    public virtual string Name { get; set; }
    public virtual IList<MyItem> Children { get; set; } = new ObservableCollection<MyItem>();
}

}

[CHIPSNetwork]

Version 2.7.4

[jiiteel]

I was able to get the arrows by modifying the App.xaml.
First add the namespace

xmlns:material="clr-namespace:UraniumUI.Material.Resources;assembly=UraniumUI.Material"

and then replace the line

<ResourceDictionary Source="Resources/Styles/Styles.xaml" />

With

<ResourceDictionary x:Name="appStyles" Source="Resources/Styles/Styles.xaml" />
<material:StyleResource BasedOn="{x:Reference appStyles}" />

The opening and closing of the nodes do not work however. So the open/closed state stays fixed to the way the node was created.

[jiiteel]

After the Uranium UI doc pages are up, I found the way to get this working in "Getting Started"
https://enisn-projects.io/docs/en/uranium/latest/Getting-Started