What should I do about low completion rates for online courses, and how can I follow up when students don't submit assignments?

The most realistic problem with online courses isn't a lack of enrollment, but that students gradually stop showing up after signing up. At the beginning, the group chat is quite lively, but after the third week, assignments drop by half, and some people even leave the live stream running without actually listening. In my experience, if recorded courses rely solely on students "managing their…