The most common reason for a survey not being recognized is that your uploads have cropped top or bottom parts. All four corner marks have to be visible in order to recognize the survey. These are used to accurately determine the locations of the checkmarks. Some budget printers ignore the bottom part and do not print it. The solution for this would be to try using a different printer.

Second, a less common reason could be that you printed the survey and then activated unique page marking. It expects a QR code on the left, but it is not there. In that case, you will need to deactivate unique page marking.