You say you bench bled the MC. But as I remember it has two compartments for fluid and the one in the rear is hard to get filled.

Might check that.

I also seem to remember that there is a rubber button/switch on top of the MC and you are supposed to push it to reset. Not sure what it resets. Maybe it is for your low brake fluid light. Of course that would have nothing to do with the pedal going to the floor.

Good luck.