RadioButton binding is (incorrectly) reset when switching between Tabs or ViewModels

[joneuhauser]

Hi,

WPF shows the same behavior (https://stackoverflow.com/questions/8568861/when-viewmodel-is-changed-to-a-different-instance-a-bound-radiobutton-is-reset-t), but I still think this is a bug.

MainWindow.xaml

<Window.DataTemplates>
        <DataTemplate DataType="{x:Type local:TabViewModel}">
            <StackPanel Orientation="Horizontal" VerticalAlignment="Top">
                <RadioButton IsChecked="{Binding !RadioButtonProperty}" Content="Value: false"/>
                <RadioButton IsChecked="{Binding RadioButtonProperty}" Margin="5, 0" Content="Value: true"/>
            </StackPanel>
        </DataTemplate>
    </Window.DataTemplates>
    <TabControl>
        <TabItem Content="{Binding VM1}" Header="Tab 1"></TabItem>
        <TabItem Content="{Binding VM2}" Header="Tab 2"></TabItem>
    </TabControl>

MainWindow.xaml.cs

 public class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new MainWindowViewModel();
        }

        private void InitializeComponent()
        {
            AvaloniaXamlLoader.Load(this);
        }
    }
    public abstract class ViewModelBase : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    public class MainWindowViewModel : ViewModelBase
    {
        public TabViewModel VM1 { get; set; }
        public TabViewModel VM2 { get; set; }
        public MainWindowViewModel()
        {
            VM1 = new TabViewModel();
            VM2 = new TabViewModel();
        }
    }
    public class TabViewModel : ViewModelBase
    {
        bool _RadioButtonProperty;

        public bool RadioButtonProperty
        {
            get
            {
                return _RadioButtonProperty;
            }
            set
            {
                if (_RadioButtonProperty == value)
                    return;

                _RadioButtonProperty = value;
                OnPropertyChanged();
            }
        }
    }

Steps to reproduce:

1. Run app
2. Switch radio button on the first tab to True
3. Go to the second tab
4. Go back to the first tab

Expected outcome: RadioButton in the first tab is still True Observed outcome: RadioButton is reset to False

Not reproduced with a CheckBox.

I don't require Group names to reproduce, so I doubt https://github.com/AvaloniaUI/Avalonia/issues/2717 or https://github.com/AvaloniaUI/Avalonia/issues/2903 are related.

Avalonia 0.9.12 and 0.10.0 on Windows 10 and Ubuntu 20.04

If this is not a bug, how can I work around it?