MasterDetailPage with TabbedPage in master page, bug ?

I'm not sure if i'm doing something wrong or if this is a bug but in certain condition, the tabbedpage don't draw the tab in the master page.
(Ipad, iOS 9.0, seems to work fine on the 8.4 images of the simulator)

• Create a Form Shared Solution
• Create a MasterDetailPage as your MainPage
• Add a TabbedPage as your Master page with some children
• Add a ContentPage as your detail page

• Set MasterBehavior as default (for ipad, split on landscape / popover on portrait)

• Launch it on the simulator in portrait mode,

• Turn your device left or right
• you have no tab
• go in portrait mode, slide left -> tab are here.
• If you turn now your ipad in landscape mode :
  
  
  • If your master page was left open, you will see the tabs
  • If your master page was closed on portrait mode, you will not see the tabs

A little code :

public class App : Application
    {
            public App( )
            {
                MainPage = new MasterDetailPage() {
                    Master = new TabbedPage() {
                        BackgroundColor = Color.Blue,
                        Title = "Master",
                        Children = {
                            new ContentPage(){Title = "T1", BackgroundColor = Color.Blue,},
                            new ContentPage(){Title = "T2", BackgroundColor = Color.Red, },
                            new ContentPage(){Title = "T3", BackgroundColor = Color.Green},
                        }
                    },
                    MasterBehavior = MasterBehavior.Default,
                    Detail = new ContentPage(){ 
                        Title = "Detail", 
                        Content = new StackLayout() {
                            Children = {
                                new Label() {
                                    Text = "Detail",
                                    VerticalOptions = LayoutOptions.CenterAndExpand,
                                    HorizontalOptions = LayoutOptions.CenterAndExpand,
                                } 
                            }
                        }}  
                };
            }
        }