System down alerts not being displayed in Administration Console

Customer configured the Access Gateway (AG) Servers -> Configuration -> Alerts options so that
system down, system up and configuration changes would get logged to the
Administraion Console. The 'Send to Device Manager:' flag was enabled which
sends alerts to the Administration Console as per the docs.

When the admin makes some config changes, and then goes to the Alert's field on
the first AG screen (beside the health check), the alert is successfully
triggered with a message 'Proxy configuration has changed.'. If a restart is 
required, the message indicating that the 

'Access Gateway is Up' 

is generated. However, when the system is downed, there is no alert notifying the admin 
of this event eg. 

"Warning - Access Gateway is down"