I’m having the exact same problem. Testmail yes, activation mail no. Checking Debug Events is no solution, because the activation emails are not visible in Debug Events. It is like no email has been sent at all. So this question sadly is not resolved at all. The WP Mail is supposed to solve this (https://wpmailsmtp.com/buddypress-activation-email-notifications/ ), but it clearly does not always do this. So where is the bug?
