One a number of occasions, we have online courses that get delivered while being built (new lessons added), or certain lessons within a course have had more critical updates that should be revisited by previously learners having completed the course.
My perfect state idea would include a toggle option on each edit lesson screen, to reset learner progress on that lesson and an "also reset course progress" toggle for refreshed lessons.
In addition or otherwise for when adding new lessons; from the course page actions, a button to "reset course progress" for all learners. This would be different that re-enroll as progress on existing lessons would stay intact, however the learner would now have the course revert to "in progress" with just the new lessons required to complete.
We need something like this as well. We update our content regularly and users are not able to see the updated content if they have previously accessed that lesson. This is causing really big issues for us and because of the size of our user base, it isn't feasible to go into each transcript and manually reset progress for updated lessons.