After upgrade to AA 8.9, the administrator password summary notification emails are configured to be sent to four separate email addresses. However, they are only being sent to the AA Admin email only. Removing all four emails and re-adding them doesn't help.
We have confirmed that this is a defect in the Password reminders where the administrator email is currently only sent to the Active Administrator owner's email address. We have created a defect to have this addressed in a future version of Active Administrator. The defect ID is 650725.