Direct2D HWND render target?

[frlis]

Hey y'all, I'm a bit of a graphics noob but I believe this code using a Direct2D HWND render target should work, yet rt.BeginDraw() causes an access violation on the very first frame:

using Silk.NET.Windowing;
using Silk.NET.Maths;
using Silk.NET.Direct2D;
using Silk.NET.Core.Native;
using Silk.NET.DXGI;

class Program
{
    private static IWindow _window = null!;
    private static D2D _d2d = null!;
    private static ComPtr<ID2D1Factory2> _factory;
    private static ComPtr<ID2D1HwndRenderTarget> _hwndRT;
    private static ComPtr<ID2D1SolidColorBrush> _rectBrush;

    static void Main()
    {
        var opts = WindowOptions.Default with
        {
            Title = "Silk.NET Direct2D",
            Size = new Vector2D<int>(800, 600),
            API = new GraphicsAPI(ContextAPI.None, new APIVersion(0, 0))
        };

        _window = Window.Create(opts);
        _window.Load += OnLoad;
        _window.Render += OnRender;
        _window.Resize += OnResize;
        _window.Run();
    }

    unsafe static void OnLoad()
    {
        _d2d = D2D.GetApi();

        Guid factoryGuid = ID2D1Factory2.Guid;
        FactoryOptions options = new()
        {
            DebugLevel = DebugLevel.None
        };

        void* factoryPtr = null;
        int hr = _d2d.D2D1CreateFactory(
            FactoryType.SingleThreaded,
            &factoryGuid,
            &options,
            &factoryPtr
        );
        if (hr < 0 || factoryPtr == null)
            throw new Exception($"D2D1CreateFactory failed: 0x{hr:X8}");

        _factory = new ComPtr<ID2D1Factory2>((ID2D1Factory2*)factoryPtr);

        var native = _window.Native
            ?? throw new InvalidOperationException("Window not initialized");

        (nint hwnd, _, _) = native.Win32
            ?? throw new InvalidOperationException("No Win32 window");

        var fbSize = _window.FramebufferSize;

        RenderTargetProperties rtProps = new()
        {
            Type = RenderTargetType.Software,
            PixelFormat = new PixelFormat(Format.FormatUnknown, Silk.NET.Direct2D.AlphaMode.Ignore),
            DpiX = 96,
            DpiY = 96,
            Usage = RenderTargetUsage.None,
            MinLevel = FeatureLevel.LevelDefault
        };

        HwndRenderTargetProperties hwndProps = new()
        {
            Hwnd = hwnd,
            PixelSize = new Vector2D<uint>((uint)fbSize.X, (uint)fbSize.Y),
            PresentOptions = PresentOptions.Immediately
        };

        ID2D1HwndRenderTarget* rtPtr = null;
        hr = _factory.CreateHwndRenderTarget(
            in rtProps,
            in hwndProps,
            &rtPtr
        );
        if (hr < 0 || rtPtr == null)
            throw new Exception($"CreateHwndRenderTarget failed: 0x{hr:X8}");

        _hwndRT = new ComPtr<ID2D1HwndRenderTarget>(rtPtr);
    }

    unsafe static void OnRender(double _)
    {
        if (_hwndRT.Handle == null)
            return;

        var rt = _hwndRT.Get();

        rt.BeginDraw();

        D3Dcolorvalue clear = new() { R = 0, G = 0, B = 0, A = 1 };
        rt.Clear(in clear);

        int hr = rt.EndDraw(null, null);
        // TODO: Handle D2DERR_RECREATE_TARGET
    }

    unsafe static void OnResize(Vector2D<int> size)
    {
        if (_hwndRT.Handle == null)
            return;

        var resize = new Vector2D<uint>((uint)size.X, (uint)size.Y);
        _hwndRT.Get().Resize(ref resize);
    }
}

Any idea why this doesn't work?