How to mark a submission as late

[ashimpi]

Through my EduApp I set grades for assignments using the submissions API, however, it seems to ignore both the late_policy_status set to "late" as well as late flag being set to true, for that matter the API does not seem to honor the submitted_at time stamp either, I am using the submissions API for submitting grades completed in an external tool. The posted grade is accepted and posted properly by the submissions API, the only issue I have is with marking the submission late, if the date it is completed is past the due_at date on the assignment. What am I missing? Any one ever tried to mark submissions as late through the API? Any help is greatly appreciated.