uwp - 为什么 AppWindow 不使用 MediaElement 打开页面？

Question

不幸的是，这个问题比标题中描述的要复杂一些。带有 MediaElement 的页面并没有真正脱落，但仅在大约四分之一的情况下。

<Page
    x:Class="Controls.Controls.VideoPlayerPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Controls.Controls"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    <Grid >
        <MediaElement AreTransportControlsEnabled="True"/>
    </Grid>
</Page>

public sealed partial class VideoPlayerPage : Page
    {
        public VideoPlayerPage()
        {
            this.InitializeComponent();
        }
        protected override void OnNavigatedTo(NavigationEventArgs e)
        {           
            this.InitializeComponent();
            base.OnNavigatedTo(e);
        }
    }

<Page
    x:Class="Controls2.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Controls2"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    <Grid  x:Name="Sp">

    </Grid>
</Page>

public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
            F();
        }
        public async void F()
        {
            for (int i = 0; i < 10; i++)
            {
                AppWindow appWindow = await AppWindow.TryCreateAsync();
                Frame appWindowContentFrame = new Frame();
                appWindowContentFrame.NavigateToType(typeof(VideoPlayerPage), null, null);
                ElementCompositionPreview.SetAppWindowContent(appWindow, appWindowContentFrame);
                await appWindow.TryShowAsync();
            }
        }
    }

同时，例如，如果创建的页面中有一个按钮（而不是 MediaElement），则一切正常。