Flyout overlapping to Menubar within the animation about mahapps.metro HOT 2 CLOSED

<mah:MetroWindow x:Class="DemoWindowSample"
                 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                 xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
                 xmlns:mah="http://metro.mahapps.com/winfx/xaml/controls"
                 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
                 Title="Demo"
...

  <mah:MetroWindow.Flyouts>
    <mah:FlyoutsControl>
      <mah:Flyout x:Name="flyoutNotif" Position="Top" AutoCloseInterval="2000" IsAutoCloseEnabled="True" CloseButtonVisibility="Hidden" Visibility="Visible">
        <TextBlock Text="Ticket Submitted" FontSize="30" HorizontalAlignment="Center" VerticalAlignment="Center" />
      </mah:Flyout>
    </mah:FlyoutsControl>
  </mah:MetroWindow.Flyouts>

</mah:MetroWindow>

<mah:MetroWindow x:Class="test.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mah="http://metro.mahapps.com/winfx/xaml/controls"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:test"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
  <mah:MetroWindow.Flyouts>
    <mah:FlyoutsControl>
      <mah:Flyout x:Name="flyoutNotif" Position="Top" IsOpen="True" AutoCloseInterval="2000" IsAutoCloseEnabled="True" CloseButtonVisibility="Hidden" Visibility="Visible">
        <TextBlock Text="Ticket Submitted" FontSize="30" HorizontalAlignment="Center" VerticalAlignment="Center" />
      </mah:Flyout>
    </mah:FlyoutsControl>
  </mah:MetroWindow.Flyouts>
  <Grid>

  </Grid>
</mah:MetroWindow>