OnPreviewFrame(IntPtr data, Camera camera) is not being called

[JJwilkin]

Hello, I am trying to access the frames of the preview on Android using this Library, and then passing the FastJavaByteArray to Zxing's Decode() method to scan for a barcode in a specific area of the preview. The preview is working fine, and when I use the normal Preview.SetPreviewCallback(this); it works fine and the OnPreviewFrame(byte[], Camera) gets called. It's just when I use Preview.SetNonMarshalingPreviewCallback(this) that the method isn't being called. I'm not to sure why this is happening and I wanted to use this so I could scan for a barcode frame by frame using Zxing. I've attached my code below.

`public void Open() {
if (!closed) return;
try {
Preview = Camera.Open();
}
catch (Exception e) {
Console.WriteLine(e);
}

		var parameters = Preview.GetParameters();

		int numBytes = (parameters.PreviewSize.Width * parameters.PreviewSize.Height * Android.Graphics.ImageFormat.GetBitsPerPixel(parameters.PreviewFormat)) / 8;
		using (FastJavaByteArray buffer = new FastJavaByteArray(numBytes))
			Preview.AddCallbackBuffer(new FastJavaByteArray(numBytes));

		var options = new ZXing.Mobile.MobileBarcodeScanningOptions();
		options.PossibleFormats.Add(BarcodeFormat.QR_CODE);
		barcodeReader = options.BuildBarcodeReader();

        Preview.SetNonMarshalingPreviewCallback(this);
        //Preview.SetPreviewCallback(this);


        Handler handler = new Handler();
        Action loop = null;
        loop = () =>
        {
            if (!closed)
            {
                AutoFocusLoop();
                
                handler.PostDelayed(loop, (long)(1000 * AF_DELAY));
            }
        };
        handler.Post(loop);

        closed = false;
    }

public void OnPreviewFrame(IntPtr data, Camera camera)
{
//Generate FastJavaByteArray and use Zxing Decode()
}

`