Called function is not changing visibility of an element- wpf c#

Question

I've got a problem with my functions. I have panel with menu:

    public void ChangeAppControlPush(object sender, MouseButtonEventArgs e)
    {
        var tag = ((StackPanel)sender).Tag;
        int i = int.Parse((string)tag);
        MenuValues.panelShowClicked = i;
        
        menuPanel menuPanel = new();
        menuPanel.ChangeWindowAppPush();
    }

which takes tag of clicked element, save's it to global variable and call function from parent window:

    public void ChangeApp()
    {
        switch (MenuValues.panelShowClicked)
        {
            case 0:
                dash.Visibility = Visibility.Visible;
                chatApp.Visibility = Visibility.Collapsed;
                break;
            case 1:
                dash.Visibility = Visibility.Collapsed;
                chatApp.Visibility = Visibility.Visible;
                break;
        }
    }

The problem is that the visibility of my elements inside the parent window is not changing - no errors or something to work with :(. Can anyone explain? Because when I do MessageBox inside ChangeApp() function with MenuValues.panelShowClicked value MessageBox is shown and value is correct. Idk what is happening.

Thanks a lot!