Adding SwipeItems to a SwipeControl from code-behind throws an AccessViolationException

Describe the bug I have been trying to add a SwipeControl to a StackPanel from a C# code-behind. Doing everything from XAML works as expected, but doing the exact same in C# always throws an AccessViolationException when attempting to add a new SwipeItem to SwipeControl.LeftItems (or any of the other four directions).

I also tried not setting LeftItems in the ‘constructor’ (not sure what it’s called) and not setting it at all. The former resulted in the same error, and the latter threw a NullReferenceException as expected.

Steps to reproduce the bug

var swipeControl = new SwipeControl()
{
    LeftItems = new SwipeItems()
    {
        Mode = SwipeMode.Execute
    }
};
swipeControl.LeftItems.Add(new SwipeItem() {
    Text = "Dismiss",
    IconSource = new SymbolIconSource()
    {
         Symbol = Symbol.Forward
    }
});

Expected behavior WinUI should not throw an AccessViolationException.

Version Info

NuGet package version: Microsoft.UI.Xaml 2.4.2 Microsoft.UI.Xaml 2.5.0-prerelease.200708003

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
May 2020 Update (19041)	Yes
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

Additional context

This should be a separate issue, but without native or mixed debugging enabled, the real exception is hidden behind a non-descriptive COM exception. The only information that can be extrapolated from that COM exception is which assembly it’s coming from (which in this case is Microsoft.UI.Xaml)

[StephenLPeters]

This is on my radar but I haven’t had the time to investigate it yet. I’m sorry.

[github-actions[bot]]

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