Why cannot I bind the value of ListBox inside TemplatedControl?

[kyuranger]

I have recently used a ListBox-related function repeatedly in my project, so I encapsulated it as a TemplatedControl for easy reuse.

This is the sample code I wrote. For convenience, I deleted all the extra ones and only kept the ListBox related ones.

TemplatedControl
XAML:

<ResourceDictionary xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
					xmlns:System="clr-namespace:System;assembly=System.Runtime"
        xmlns:controls="using:AvaloniaApplication2">
  
  <Design.PreviewWith>
    <StackPanel Width="400" Spacing="10">      
        <StackPanel Background="{DynamicResource SystemRegionBrush}">
          <controls:ListBoxTemplatedControl />
        </StackPanel>
    </StackPanel>
  </Design.PreviewWith>
 
  <ControlTheme x:Key="{x:Type controls:ListBoxTemplatedControl}" TargetType="controls:ListBoxTemplatedControl">
    <Setter Property="Template">
      <ControlTemplate>
		  <ListBox ItemsSource="{TemplateBinding AvailableThemeOC}" Margin="0,0,20,0" Name="PART_ListBox" SelectedItem="{TemplateBinding CurrentTheme}" Background="Transparent">
			  <ListBox.ItemTemplate>
				  <DataTemplate x:DataType="System:String">
					  <TextBlock Text="{Binding }"></TextBlock>
				  </DataTemplate>
			  </ListBox.ItemTemplate>
			  <ListBox.ItemsPanel>
				  <ItemsPanelTemplate>
					  <StackPanel></StackPanel>
				  </ItemsPanelTemplate>
			  </ListBox.ItemsPanel>
		  </ListBox>
      </ControlTemplate>
    </Setter>
  </ControlTheme>
</ResourceDictionary>

Code-Behind

using Avalonia;
using Avalonia.Controls.Primitives;
using System.Collections.ObjectModel;

namespace AvaloniaApplication2;

public class ListBoxTemplatedControl : TemplatedControl
{
    public static readonly StyledProperty<ObservableCollection<string>> AvailableThemeOCProperty =
AvaloniaProperty.Register<ListBoxTemplatedControl, ObservableCollection<string>>(nameof(AvailableThemeOC));

    public ObservableCollection<string> AvailableThemeOC
    {
        get { return GetValue(AvailableThemeOCProperty); }
        set { SetValue(AvailableThemeOCProperty, value); }
    }

    public static readonly StyledProperty<string?> CurrentThemeProperty =
AvaloniaProperty.Register<ListBoxTemplatedControl, string?>(nameof(CurrentTheme));

    public string? CurrentTheme
    {
        get { return GetValue(CurrentThemeProperty); }
        set
        {
            SetValue(CurrentThemeProperty, value);
        }
    }
}

ViewModel:

using CommunityToolkit.Mvvm.ComponentModel;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AvaloniaApplication2
{
    public partial class ViewModel:ObservableObject
    {
        [ObservableProperty]
        ObservableCollection<string> _AvailableThemeOC = new ObservableCollection<string>(["123","456","789","000"]);    

        string _CurrentTheme="";
        public string CurrentTheme
        {
            get => _CurrentTheme;
            set { 
                if (_CurrentTheme != value)
                {
                    _CurrentTheme = value;
                    OnPropertyChanged();
                }
            }
        }
    }
}

View
XAML:

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="AvaloniaApplication2.MainWindow"
		xmlns:Local="using:AvaloniaApplication2"
		x:DataType="Local:ViewModel"
        Title="AvaloniaApplication2">
	<Local:ListBoxTemplatedControl AvailableThemeOC="{Binding AvailableThemeOC}" CurrentTheme="{Binding CurrentTheme,Mode=TwoWay}"></Local:ListBoxTemplatedControl>
</Window>

Code-Behind:

using Avalonia.Controls;

namespace AvaloniaApplication2
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            this.DataContext= new ViewModel(); 
        }
    }
}

For your convenience, I have packaged the source code of the entire example project.
AvaloniaApplication2.zip

After the program runs, there are no errors. But if you add a breakpoint to the Set method of CurrentTheme in ViewModel, you will find that it is not triggered at all.

In other words, the value of CurrentTheme in ViewModel will not change at all. What is the reason for this?

[rabbitism]

twoway