Air Bag Not Deploy problems of the 2014 GMC Sierra

I was stopped at a red light behind 2 other vehicles. A vehicle from behind struck me at appx 40 mph and rammed me into vehicle in front of me. The cab of my truck filled with a white. "smoke". I was told by both firemen and wrecker driver airbags had activated but not deployed. My wife was with me. Both our seatbelts locked up as they should. Concern is had the airbag deployed it might have helped with back and shoulder injury. Maybe we would not have bounced around as much. I notified GMC and they made a case file but after a week still have not contacted me. Even after numerous voice messages left.