Very common issue with brembo calipers. The calliper being alloy and the bleed nepple made of steel make not the best combination. the 2 metals react, corrode and seize in effect.
I sheared 2 nipple threads last time I wanted to bleed the rear brakes, but I fixed them myself by helicoiling the thread in calipers and getting the stainless steel bleed nipples off eBay.
As far as I know Godspeed offers the refurbished ones on exchange basis.