Net Maui Navigation Back button

Question

I have a problem with understanding the back button and the behaviour.

I create an own Title view and like to have the back button if necassary. In WinUI this works as expected but on the Android emulator I only get a white field.

Can anyone explain this bahaviour. And what ist to do integrate/add the back button?

<Shell.BackButtonBehavior>
 <BackButtonBehavior  
     IsVisible="True"/>
   </Shell.BackButtonBehavior>
<Shell.TitleView  >     
 <Grid  BackgroundColor="{StaticResource EbmPapstLightBlue}" 
        HorizontalOptions="Fill" 
        VerticalOptions="Fill">
     <Label Text="{Binding Path=TitleForHeader}" 
            FontSize="16" 
            TextColor="White"                
            FontAttributes="Bold" HorizontalOptions="Center" VerticalOptions="Center"/>
     <Image Margin="5" HorizontalOptions="End" Aspect="AspectFill" Source="test.png" 
 MaximumWidthRequest="50"  />
 </Grid>

</Shell.TitleView>

I am using .net 8 and maui 8.0.3. it seems that the complete back button behaviour will Not work correctly