Computer Not Reachable Problems With The SCOM Console But Goes Well With The Notification

Hi ;

I've a weird scenario. It goes like this :-

Situation:- The Computer Not Reachable monitor is ENABLE.

Problems :-

We can receive the notification of any down servers via email ( this works for all servers). But the weird thing is ,the alert didn't appear in the Console for some  servers . Example , if I receive the email for 10 servers, only five of them appear in the console. Therefore, we have to depend on email rather than the console.Even if we create a custom view of the alert to see number of closed alert , we still couldn't see some of them. 

One thing that I notice in the monitor Override Properties is this :-

Monitor Name : Computer Not Reachable

Category         : State Collection

Override target : Group: Managed Computer Client Health Service Watcher Group

Parameter Name :Generates Alert

Boolean Parameter Type : Generates AlertBooleanDefault Value :True

Override Value  :False

Effective Value  : False

Could the above setting be the reason ? If yes, how come it works for certain servers. Btw, is there, any possibility that I can trace who made such override ?

Thanks for your help.