I have been trying to create an updated version of the xAPI Launch Link plugin (Moodle plugins directory: xAPI Launch Link) which adds the ability to read grade data from the "Results" section of an xAPI statement into Moodle. My fork is available here: Vjedi729/moodle-mod_tincanlaunch (github.com).
My current problem, is that despite implementing the functions listed in Gradebook API, the assignment grade column does not appear in the Gradebook. I have confirmed that the CRON task for reading in the grades has run and that the grade information is present in the "Results" section of the xAPI statement in the LRS. I believe that the issue is before the grades are checked, since there isn't even a blank grade in the gradebook, but I don't have the background to know for sure.
I am not well versed in PHP, so my ability to debug is somewhat limited. Any advice, either on my problem or Moodle activity plugin development or PHP debugging, would be appreciated.