I'm using the submissions api to pull the students' marks across multiple courses, recently I've started getting 403 Error (Forbidden) on some but not all courses that I'm accessing and only when passing something using the asssignment_ids[] parameter. 

I"m using this: 

api/v1/courses/:course_id/students/submissions

with the assignment_ids parameter being passed a list of the assignments I want to get the data for , grouped = True and student_ids[] set to all. 

I've checked that I can access the assignments themselves so the ids I'm passing aren't the issue, and the submissions are retrieved when I clear the assignment_ids[] parameter.