I noticed yesterday that my progression status was lost on the course
It might be somewhat related to this issue because @elaine_rosenber updated the course 2 days ago, shortly before I noticed the issue.
This missing getQuizStatus probably explains why the status is lost and subsequently why the completion certificate is unavailable.
What happens if you enroll in the course again and complete the quizzes again. Each section will have a green highlight if the quiz has answers submitted.