What rear tire are you using? Also, you stated that blacks didn't work, were you saucing the entire tire and it still loaded up?

Based on various discussions it seems there are 2 different situations that lead to a loss in front traction.
One is a jack the gripper problem where saucing the entire front keeps the rubber clean and using blacks keeps it drivable for the whole 8 minutes.

The other situation is when the fronts are getting overworked(and overheated) because the rear is too locked in. Reducing rear traction with chassis tuning or switching to a lower grip tire in the rear to free it up (grey) lets the car steer more with less load on the front.

i had the first situation, while it sounds like you may have the second.