confusion over distrobution/proportioning block

Check for leaks inside the car at the master cyl. The rear ports / piston on the MC is for the front brakes. My MC leaked there and went between carpet and body. You would have never known.

When you re-bleed the brakes are you getting air bubbles out?

Have you tried gravity bleading the front discs?
I had a car that took weeks to get the trapped air out from a MC replacement, o must have bleed a pint of fluid thru it.