Hi guys
I had same problem and finally the thing was that the option to send a test email is not working so the best way to know if it's working really is to create an order and change order status to check if the system sends the email. Usually you get a text message in order page on a few seconds.
In my case it was working, emails were sending but because I've just focus on test mail tool I thought that It wasn't.
This was with Prestashop version 8.1.3
Hope this helps 