RBE does not send notifications. bbpnns does. RBE simply processes messages it finds in the connected mailbox.
The Dry run clearly shows that it is not finding any accounts subscribed to the forum whose topic you selected.
> There are currently 3 members in the group.
I found our email conversation from Dec/Jan. Are you still using Private Groups? Is this the group you are referring to?
If so, and you’re still using Private Groups Bridge, then the simplest solution is to select the Subscriber role in bbpnns settings. The Private Groups Bridge will talk to Private Groups and ensure that only the correct users get notified.
You see, bbpnns pulls all users from a role or the users that have actually subscribed to bbPress forums and topics. The bridge weeds out those who cannot see the forum/topic using Private Groups’ rules. Because you don’t have any role selected and no users are actually subscribed using bbPress core subscriptions, then there’s nobody to notify or weed out.
I hope this helps.