Issue WPF with ViewModel and IsEnabled Databinding

Question

We have an issue with WPF ViewModel and IsEnabled databinding.

It's about a WPF Skype application which should activate buttons when a call is connected. However, this only works if the MainWindow is focused afterwards.

MainWindows loaded:

The buttons are only activated when we bring the main window to the foreground or activate it.

MainWindow.xaml.cs

namespace Skype_CTI.Views
{
    /// <summary>
    /// </summary>
    public partial class MainWindow : MetroWindow
    {
        public MainWindow()
        {
            InitializeComponent();
        }


    }
}

MainWindow.xaml

        <Button x:Name="adhoc_profil" Content="Open Ad-hoc profile" ToolTip="" HorizontalAlignment="Left" Margin="338,199,0,0" VerticalAlignment="Top" Width="170" Command="{Binding OpenBrowserWithAdhocProfil_Command}" Grid.Column="1" Height="20" IsEnabled="{Binding IsAdhocProfilEnable}"/>

MainWIndowViewModel.cs

 private bool _isAdhocProfilEnable;

        public bool IsAdhocProfilEnable
        {
            get { return _isAdhocProfilEnable; }
            set { SetProperty(ref _isAdhocProfilEnable, value); }
        }
        
        ...
        
         public MainWindowViewModel()
        {
            _logger.Info("MainWindowViewModel CTOR reached!");
            _incomingCall = 0;
            _outgoingCall = 0;
            _isAdhocProfilEnable = false;
            
            ...
            
             if (e.NewState == ModalityState.Connected && _incomingCall == 1)
                {
                ...
                 Application.Current.Dispatcher.BeginInvoke(new Action(() =>
                            {
                                try
                                {
                                ....
                                IsAdhocProfilEnable = true;
                                ....
  

Can anyone help?

Thanks a lot