A graded assignment in your course may show as Due or not be marked as Completed if you are missing a green check mark in that section, but this does not affect your grading or certificate status. Sometimes advanced assignment types might not receive the green check mark, or there will be a delay before they display as completed (for example, proctored exams).
Your scores and your eligibility for the certificate are determined by the points you earn on graded assessments as reflected on your Progress page. You can qualify for the certificate as long as you earn a passing score before the course ends.
A missing check mark will not negatively affect your Progress score or prevent you from earning the verified certificate.