CommandBarFlyout has gap between primary and secondary commands when secondary are shown above.

Describe the bug CommandBarFlyout has gap between primary and secondary commands when secondary are shown above primary due to the constrained space. Gap is shown only first time, bug could be repeated with both WUX and MUX 2.6.2 versions of CommandBarFlyout, everything was tested on OS 19043

Steps to reproduce the bug

1. VS2019, new blank C++/CX app, target 19041, min target 17763
2. Add button aligned to the bottom of page with attached CommandBarFlyout

    <Page.Resources>
        <CommandBarFlyout x:Name="CommandBarFlyout1">
            <AppBarButton Label="Share" Icon="Share" ToolTipService.ToolTip="Share" />
            <AppBarButton Label="Save" Icon="Save" ToolTipService.ToolTip="Save" />
            <AppBarButton Label="Delete" Icon="Delete" ToolTipService.ToolTip="Delete" />
            <CommandBarFlyout.SecondaryCommands>
                <AppBarButton x:Name="ResizeButton1" Label="Resize"/>
                <AppBarButton x:Name="MoveButton1" Label="Move"/>
            </CommandBarFlyout.SecondaryCommands>
        </CommandBarFlyout>
    </Page.Resources>

    <Button VerticalAlignment="Bottom" Content="Show Flyout" Flyout="{StaticResource CommandBarFlyout1}"/>

1. Press button - flyout is shown with gap between primary and secondary commands
2. Press button again - flyout is shown without gap between primary and secondary commands

Expected behavior CommandBarFlyout should show secondary commands above primary ones without any gap between

Screenshots Windows.UI.Xaml version

Microsoft.UI.Xaml version from XamlControlsGallery

Microsoft.UI.Xaml version 2.6.2 in ControlsResourcesVersion=“Version1” mode

Version Info CommandBarFlyout from both Microsoft.UI.Xaml 2.6.2 and Windows.UI.Xaml has this bug Host OS 19043.1165 UWP App, WinUI 2.6.2

Windows app type:

UWP	Win32
Yes

Windows version	Saw the problem?
Insider Build (xxxxx)
May 2021 Update (19043)	Yes
October 2020 Update (19042)
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

[zhuxb711]

They just don’t want to fix this issue since I mention it on Aug, 2020 #3209

[zadjii-msft]

Not to necro an old thread, but we saw this with the Terminal too - until we switched to the Microsoft.UI.Xaml.Controls:CommandBarFlyout version. Then it just worked like a charm. We were able to do that as a drop-in replacement, just change the namespace.

Figured that future readers may find that helpful.