Note – this may not be the final solution, so ensure the original file can be put back in case of any issues. But don’t worry, this will / can NOT harm or change any data, regardless of whether it works or not.
Just replace the file kiwitrees/individual.php with the new copy from the attached zip file. Clear your browser cache then close and restart the browser (these actions designed to ensure existing cookies are no longer active).
Once back to your site, carry out the same actions you originally reported and see if you get a better outcome.