Did the achievement glitch on your account?
Did you start out on SuperSoldier Difficulty?
Did the Veteran 3/7 achievement unlock?
Did you access the tutorial from a new game or through the menu?
Prior to campaign completion, did you replay missions through mission select?
If it didn't unlock initially, how did you finally get it to pop?
The only way ive heard how to get this achievement is by wiping your game save, playing the game through on Normal and then on SS :/
Did you press the X button to skip cutscenes either at the end of a chapter or during a mission