By the way, I mapped MB to Left Trigger; my fightpad's configuration has LT on the right side of the controller. I seem to get it out quite nicely on Training mode, but here it's rabidly impossible to pull MB off online.
You are double tapping your first input. Let's take Smoke Bomb. Go into training mode and see for yourself. DD3 MB will meter burn smoke bomb, now hit DD 33 and hit MB. It will not come out. I had this exact same problem.