I did not success with 100% when I used Coursera’s ChatGPT 3.5 lab, which is the recommended chat (link included in lessons) in the course. But when I changed to use chatgpt.com with free account (new credits every 3 hours) I did finally get 100% score in notebook’s internal checking method and in submitted notebook checker also. So I did pass the test 100%.
Another hint is to use reset kernel & run all cells. Sometimes notebook did get some errors and resetting is the solution.