This beta group has been going on for a year, early 2019. Our retention rate is really poor, until today's posting about 400 signups and only 8 made it to the end. The current first phase is actually to answer this question:

"For the students that complete the whole curriculum, could they contribute to a codebase that users use and follow good coding practices like an engineer would?"

The answer is yes, so now we have a happy path. Next phase is to increase this funnel.

I'm curious to learn what you plan to do in order to understand the retention rate issues

When students engage with me to ask questions, I usually just ask them directly: "If you decide that this isn't for you, please let me or someone else on the team know before you do so we understand how we can make this a better learning platform for future students"

Have you discovered patterns? I've done some research work on remote learning, so genuinely curious.

not enough engagement. If I reach out to students and engage in conversations with them regularly, they have a higher chance of following through. I start high up in the funnel, to pay utmost attention to students who are at the end (JS6). Then when I have free time, I go down the funnel and pull students up. As I polish the end, I get more and more time to engage with students lower in the funnel. I just reach out and say hi, ask them why they are learning and if they have any questions and concerns.

That sounds great, the way you are doing it. I think companies end up gamifying the product approach,to generate feelings that are similar to what happens when you engage one on one (from a neuroscience perspective)