They don't sell ads on their service. Engagement in the way you keep using it isn't important as it is to a service that does sell ads. As that is what companies look for when purchasing a timeslot. Amazon doesn't need to hide any losses from the show. It broke internal records for Prime Video. It made top 15 streaming. It has award nominations. It has been stated to have more than paid off the investment.
You are another that is having trouble accepting that the show could be a success. Why? Why are you so desperate to continually claim the show is a failure?