Confirm that the Event details are populated in the AA Alerts:
If the Event Details of the alert has data, try changing the SMTP Settings to Plan Text for the Message format instead of HTML
If the Event Details of the alert did not have data, check the event that was logged in the Security Event log of the DC to confirm that the additional data is shown in the event. If the event on the DC has the extra details contact Support to troubleshoot AA further.