Unable to progress to next unit

I am not exactly sure what is going on with my install. It seems as if all of the students are locked into the current progress within a unit no matter how far they have progressed. This seems to be preventing them from continuing to the next unit in a course. I have already deactivated and reactivated plugins to try and troubleshoot the problem.

After looking into the issue a little more it appears that the students are only getting stuck on a particular unit. This unit has a file upload that is mandatory and assessable. I have assigned a grade to the uploads, but the student's progress is locked at 75%. All pages in the unit have been completed.

Thoughts or suggestions?