Brakes keep going dead
 

So Iv got a 05 f4i with a brembo master cylinder and a hohey 4 piston caliper for my hand brake, and the stock foot brake, after riding for a little bike they both just die on me and stop working, almost like there's no brake fluid in them. The hand brake does it more often the the foot brake, Iv bleed them both and it still has the issue. My friends 636 has the same issue with his hand brake. Has anyone had this issue before? How do I fix it? Any advice is appreciated.