Cold rolled is variable so it could be that you are just unlucky with this batch.
Also you are being greedy wanting a 79% thread in cold rolled.
What kind of tap are you using? For a through hole it can be a spiral point machine tap; these are much stronger than the spiral flute type.
On occasion I have had success on difficult to tap steel using taper taps intended for manual tapping.
Also have you tried tapping partway through, coming out and going back in? I will admit this sometimes fails because the tap does not re-enter the thread correctly but with luck it can work.