I am looking for the absolute BEST way to report student progress AND grades to the principals of my online students. I have tried FN Mark manager, and the mentor/mentee reports, but they just don't impress me. I need something that can report the student's progress (especially if they have overdue assignments) and grades.
A starting place would be to use Activity Completion in your course. Setting up activity completion criteria (which can track completion based on one of several criteria) can allow you to use several built in or add on report/blocks.
The Course Completion report should show what is completed so far and what is overdue. If you use a Moodle Host, they typically will be able to create custom reports. If you use an Student Information System, you could pull data from Moodle and manipulate it as well.
Moodle 3.2's roadmap talks about updating the reporting system. There is also a great conversation going in the forums about Learning Analytics -- you may want to provide some input there.