In the nas probe , create 2 different "Profiles" under the "Auto-Operator" tab.
1) First profile ("Test_Invisible") will be used to have your server being down alarms invisible.
2) Second profile ("Test_Delay") will be used to make your previous invisible alarms visible after a certain amount of time.
3) You can test creating a test alarm "this is a test" with the matching word "test". Once created, the alarm became invisible (per Test_Invisible profile).
4) Then, in test_Delay profile chose "Action mode" = "On overdue age = 10 min". With this, you will made the invisible alarm visible after 10 minutes. You can choose between 5, 15, 60 and 90 minutes.