2 options gents.
Worth a try is to buy a 250ml syringe from a doctors and fill it with brake fluid of your choice. Attach using a suitable tube to the bleed nipple and open the master clyinder with the brake pedal open, i e. In its resting position. You can bleed brakes and clutches this way in seconds. 2nd option is to look at the reservoir for the MC. I drilled and fitted an old schrader valve from a innertube. I then fill the MC., pump up to say 2 bar and then try std bleeding. Works only for max three stokes. The de-pressurise, refill and start again
I guess the the MC seals are AWOL if these two methods dont work