Dr. DIFF cobra brake/ master cylinder question

how are you bleeding it? and you're saying you still get bubbles out at the wheel cylinders? if there are no leaks at the fittings, i'd suspect the wheel cylinders. might be pulling air in past the seals

edit: it's not losing fluid is it?

Two man system, we checked the wheel cylinders and did not see any sign of leaking. Not losing any fluid either.