Bueno -
That's one 3070 lighting up all those plants?!?
Is it on a a motorized tracker of some sort that sweeps back and forth, or is the light fixed?
Are you shuffling these plants around so that each gets a turn under the COB?
Were all these plants recently moved under the 3070 from some other area? Or has it been this way from seed/clone?
Did you swap from a 5000K to a 3000K (or 2700K) when you flipped to 12/12?
It looks like the area is at least 2 ft. X 2ft. 12 plants. They all look healthy and relatively uniform. It's hard to imagine one CXA, even if it's being driven hard, taking care of everything.