Error decoding some QR codes with error correction level H

[Anlo2846]

First of all, thanks for a great library. I have discovered an issue decoding QR codes using error correction level H. I'm running the latest version 0.16.9 from NuGet.

      BarcodeWriter writer = new BarcodeWriter()
      {
        Format = BarcodeFormat.QR_CODE,
      };

      BarcodeReader reader = new BarcodeReader()
      {
        Options = new DecodingOptions()
        {
          PossibleFormats = new List<BarcodeFormat>()
          {
            BarcodeFormat.QR_CODE,
          },
        },
      };

      Trace.WriteLine($"Level\tPixel size\tSuffix\tSuccess");
      foreach(ErrorCorrectionLevel level in new[] { ErrorCorrectionLevel.L, ErrorCorrectionLevel.M, ErrorCorrectionLevel.Q, ErrorCorrectionLevel.H })
      {
        foreach(int pixelSize in new[] { 2, 4, 8 })
        {
          foreach(string suffix in new[] { "", "suffix" })
          {
            writer.Options = new QrCodeEncodingOptions()
            {
              QrVersion = 6,
              ErrorCorrection = level,
              Width  = 49 * pixelSize,
              Height = 49 * pixelSize,
            };

            using Bitmap bmp = writer.Write("WIFI:S:Maskinutbildning;T:WPA;P:fWpzCSgnxe;;" + suffix);
            Result result = reader.Decode(bmp);
            Trace.WriteLine($"{level}\t{pixelSize}\t{suffix.Length > 0}\t{result != null}");
          }
        }
      }

This produces the output:

Level	Pixel size	Suffix	Success
L	2	False	True
L	2	True	True
L	4	False	True
L	4	True	True
L	8	False	True
L	8	True	True
M	2	False	True
M	2	True	True
M	4	False	True
M	4	True	True
M	8	False	True
M	8	True	True
Q	2	False	True
Q	2	True	True
Q	4	False	True
Q	4	True	True
Q	8	False	True
Q	8	True	True
H	2	False	True
H	2	True	True
H	4	False	False
H	4	True	True
H	8	False	False
H	8	True	True

As you can see, error correction level H is only decoded correctly when using pixel size 2. The strange thing is that if I add some more text to the QR code it decodes fine. Also if I change the password field to something other. So I guess that this exact string creates some difficult pattern in the code.

I tried an online QR code generator with the same string and error correction level H which is also not decoded by ZXing.Net.

[micjahn]

There is something wrong with the detector if the default mode is used.
If you switch to PureBarcode mode success will be true in all cases.

                Options = new DecodingOptions()
                {
                    PureBarcode = true,
                    PossibleFormats = new List<BarcodeFormat>()
...

PureBarcode mode should only be used for "synthetic" images. It doesn't work with real-world captured images.
Sorry, I don't have any idea how to fix this.