I appreciate the time you took to attempt to troubleshoot the issue we’ve had with the RBE notifications not sending to any members other than the topic author, even after the settings you suggested.
On your recommendation of using the Buddypress Bridge, we did purchase, install and test the notifications again. The Dry Run test indicated that the notification will be sent only to the group members (for both Topics and Replies). However, in reality, all users with the user roles set in BBPNNS received the notifications. This is after selecting the checkbox in Buddypress Bridge which you recommended – “Notify all members of the author’s group”.
I.e., it is now doing the opposite of the initial problem and sending the notification to all users instead of none.