ContentControl doesn't update ControlTemplate when moved to another container (parent changes)

[marbel82]

• .NET Core Version: 5.0.301
• Windows version: 10 (20H2)
• Does the bug reproduce also in WPF for .NET Framework 4.8?: Yes

Problem description:
ContentControl doesn't update ControlTemplate when moved to another container (parent changes). Is it a bug or the correct action?

Minimal repro:

I have two StackPanels. Each of them has defined a DataTemplate of the same LineItem type. When I move ContentControl from one to the other container I suspect that the view of the items will change. But it doesn't happen.

Create "WPF App (.NET 5)" or "WPF App (.NET Framework)" project and override MainWindow files:

<Window x:Class="WpfApp7core.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        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"
        xmlns:local="clr-namespace:WpfApp7core"
        mc:Ignorable="d"
        Title="MainWindow" Height="300" Width="600">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>

        <TextBlock Text="Column 1" HorizontalAlignment="Center"/>
        <TextBlock Text="Column 2" HorizontalAlignment="Center" Grid.Column="1"/>

        <StackPanel x:Name="column1" Grid.Column="0" Grid.Row="1">
            <StackPanel.Resources>
                <DataTemplate DataType="{x:Type local:LineItem}">
                    <StackPanel Orientation="Horizontal">
                        <TextBlock Text="{Binding Name}" Margin="4,0"/>
                        <TextBlock Text="{Binding Value}" Foreground="Blue"/>
                    </StackPanel>
                </DataTemplate>
            </StackPanel.Resources>
            <!-- The place where new ContentControls are added.  -->
        </StackPanel>

        <StackPanel x:Name="column2" Grid.Column="1" Grid.Row="1">
            <StackPanel.Resources>
                <DataTemplate DataType="{x:Type local:LineItem}">
                    <StackPanel Orientation="Horizontal">
                        <TextBlock Text="{Binding Name}" FontWeight="Bold" Margin="4,0"/>
                        <TextBlock Text="{Binding Value}" Foreground="Green"/>
                    </StackPanel>
                </DataTemplate>
            </StackPanel.Resources>
            <!-- The place where new ContentControls are added.  -->
        </StackPanel>

        <StackPanel Orientation="Horizontal" Grid.Row="2" Grid.ColumnSpan="2">
            <Button Content=" Create in 1 " Click="Create1_Click"/>
            <Button Content=" Create in 2 " Click="Create2_Click"/>
            <Button Content=" Move to > " Click="MoveTo2_Click"/>
            <Button Content=" Move to &lt; " Click="MoveTo1_Click"/>
        </StackPanel>
    </Grid>

</Window>

namespace WpfApp7core
{
    public class LineItem
    {
        public string Name { get; set; }
        public string Value { get; set; }
    }

    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Create1_Click(object sender, RoutedEventArgs e)
        {
            var li = new LineItem { Name = "Left", Value = Guid.NewGuid().ToString() };
            column1.Children.Add(new ContentControl { Content = li });
        }

        private void Create2_Click(object sender, RoutedEventArgs e)
        {
            var li = new LineItem { Name = "Right", Value = Guid.NewGuid().ToString() };
            column2.Children.Add(new ContentControl { Content = li });
        }

        private void MoveTo2_Click(object sender, RoutedEventArgs e)
        {
            foreach (FrameworkElement item in Enumerable.Range(0, column1.Children.Count).Select(i => column1.Children[i]).Cast<FrameworkElement>().ToList())
            {
                RemoveFromParent(item); // Remove from column1
                column2.Children.Add(item); // Add to column2
            }
        }

        private void MoveTo1_Click(object sender, RoutedEventArgs e)
        {
            foreach (FrameworkElement item in Enumerable.Range(0, column2.Children.Count).Select(i => column2.Children[i]).Cast<FrameworkElement>().ToList())
            {
                RemoveFromParent(item); // Remove from column2
                column1.Children.Add(item); // Add to column1
            }
        }

        public static void RemoveFromParent(FrameworkElement child)
        {
            switch (child.Parent)
            {
                case Panel panel: panel.Children.Remove(child); break;
                case Decorator decorator: decorator.Child = null; break;
                case ContentControl contentControl: contentControl.Content = null; break;
                case ContentPresenter contentPresenter: contentPresenter.Content = null; break;
                default: throw new Exception($"Unknown parent type {child.Parent.GetType()}");
            }
        }
    }
}

Expected behaviour:
Each items on the left should be blue, and each on the right should be green.

Unwanted solution:
I found one solution. When I assign Content to null and then assign the previous value, ContentControl will update its view.

            foreach (FrameworkElement item in Enumerable.Range(0, column1.Children.Count).Select(i => column1.Children[i]).Cast<FrameworkElement>().ToList())
            {
                RemoveFromParent(item);
                column2.Children.Add(item);

                if (item is ContentControl cc)
                {
                    var prev = cc.Content;
                    cc.Content = null;
                    cc.Content = prev;
                }
            }

But this solution becomes complicated when you have an extensive view tree.