We all have those buyers who make an order and when you deliver they just take it and leave without saying anything, ratings and reviews would help a lot, so this is how I deal with buyers.
When I deliver the first time, I explain to the buyer what I did to make him feel that I made an effort and took good care of his order (not just a lie, you have to do it and deliver your best), then I say " if you see any mistakes or need any changes please tell us", this will show that I care about his satisfaction more than just getting the money and rating, and this helped me get all ratings with 5 stars and great reviews (not even a single 4 star rating) also great tips, when the buyer feels that you care and willing to make him satisfied, he will be super nice to you and you gain a potential repeated seller.
For buyers who don’t respond after you deliver, they might be new buyers and not familiar with the site, so they think when they get the order that’s it, they take it and leave.
What I do is wait 24 hours after I deliver if he does not respond I send him this message in the order page: " Hi, please if everything is ok, “Review and complete” the order and leave us a feedback, if not, please tell us what’s wrong and we will make sure to fix it"
This is my tip that I use when dealing with buyers, hope it helps %%-