What, exactly, was Obama doing that night? The President dies not just disappear!
It lasted 15 to 20 minutes.
This would have been shortly after the end of the first attack. They may have assumed incorrectly that the attack was truly over, and maybe Obama decided to go to the powder room to prepare for the Vegas fundraiser.
A new attack was about to begin at the CIA annex at 5:30 PM EST or so that would last for 90 minutes:
SEPTEMBER 11, 2012 5:30pm EST to 7pm EST / 11:30 PM [Benghazi time] to 1 am Benghazi time SEPTEMBER 12, 2012 : (LIBYA : BENGHAZI : CIA ANNEX : FIGHTING )
SEPTEMBER 11, 2012 7pm EST / SEPTEMBER 12, 2012 1:00 AM [LIBYA TIME] : (LIBYA : BENGHAZI : A SECOND CIA TEAM ARRIVES AT THE AIRPORT IN BENGHAZI BUT HAS TROUBLE FINDING TRANSPORTATION TO LEAVE THE AIRPORT IN AN EFFORT TO FIND AMBASSADOR STEVENS)
SEPTEMBER 11, 2012 11:00 PM EST / after 5:00 AM Benghazi time SEPTEMBER 12, 2012 : (LIBYA : BENGHAZI : AFTER BEING HELD UP AT THE AIRPORT, THE SECOND CIA TEAM ARRIVES AT THE CIA ANNEX IN A LULL IN THE FIGHTING ; ALL THE SURVIVING AMERICANS ARE HOLED UP THERE)