title: xamarin navigation bar not showing TitleView
body: <p>New to Xamarin and I'm trying to create a custom navigation bar in my Cross-Platform App. After some reading I found that I might be able to use the the title-view  component in my xaml page file like below.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8" ?&gt;
  &lt;ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
               xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
               x:Class="amici.MyGroups"&gt;
      &lt;NavigationPage.TitleView&gt;
          &lt;StackLayout Orientation="Horizontal" VerticalOptions="Center" Spacing="10"&gt;
              &lt;Label HorizontalOptions="StartAndExpand" Text="Left"/&gt;
              &lt;Label HorizontalOptions="CenterAndExpand" Text="Center"/&gt;
              &lt;Label HorizontalOptions="EndAndExpand" Text="Right"/&gt;
          &lt;/StackLayout&gt;
      &lt;/NavigationPage.TitleView&gt;
  
      &lt;ContentPage.Content&gt;
          &lt;ScrollView&gt;
              &lt;Grid x:Name="grid1"&gt;
                  &lt;StackLayout&gt;
                          &lt;Label Text="Welcome"
                          VerticalOptions="CenterAndExpand" 
                          HorizontalOptions="CenterAndExpand" /&gt;
                      &lt;/StackLayout&gt;
                     &lt;ActivityIndicator x:Name="WaitIcon"  IsRunning="{Binding IsBusy}" VerticalOptions="Center" HorizontalOptions="Center" /&gt;
              &lt;/Grid&gt;
          &lt;/ScrollView&gt;
      &lt;/ContentPage.Content&gt;
  &lt;/ContentPage&gt;
  </code></pre>
  
  <p>I navigate to my page "MyGroups" like this :  Navigation.PushAsync(new MyGroups());.</p>
  
  <p>However, the only thing that shows is the default navigation page with the back icon arrow?</p>
  
  <p>obliviously I missing something, or I don't understand something. Does this need to be done at the application level?</p>