Issue where .Navigation.PushAsync(page); is not displaying a back button or the new page title

Hi guys,
I have started calling XF from within an existing iOS, Droid, PCL based solution that is NOT XF based. Im using XF initially for some screens internally, such as for Settings. I can display the initial form, but when I try to display another form within it I am not getting a Back button and the Title doesn't change to the new page, and the Done button is still visible.

The code to display the XF Settings dialog below. I have to set the pageController Title otherwise the page title isn't displayed. I also add a Done button:
`
private void DisplaySettings()
{
var page = App.GetSettingsPage();
var pageController = page.CreateViewController();
pageController.Title = page.Title;

        var navController = new UINavigationController(pageController);

        pageController.NavigationItem.RightBarButtonItem = new UIBarButtonItem(UIBarButtonSystemItem.Done, 
            delegate
        {
            navController.DismissViewController(true, null);
        });

        PresentModalViewController(navController, true);
    }

`

and the call to push a sub page:

Command<Type> navigateCommand = 
                new Command<Type>(async (Type pageType) =>
                {
                    Page page = (Page)Activator.CreateInstance(pageType);
                    await this.Navigation.PushAsync(page);
                });

I would expect the above command to push the new page onto the stack, display the new title and show a back button. It doesn't however, it still displays the initial title and the Done button, but the new page is at least displayed.

Any suggestions to resolve?

Thanks
John