I removed calipers to replace seals. Connected everything up again..added brake fluid and started pumping to bleed but getting no resistance. Level not doing anything either. Could master cylinder be a problem?

its because there is no fluid, the seals have a hard time pulling it through.

most suck it through via the caliper and once you get a fair amount of fluid going, it should operate as it should.

Took me 2 days on my twin caliper setup to do mine.

do a search on the forum as its a common issue.

Is the fluid coming out the bleed nipple? If not then you need to get suction on it or reverse pump the fluid from the nipple up to the master cylinder. If the fluid has pumped through to the nipple and all the air has come out of the system then you need new seals.

good news..left it for awhile after a million pumps and when I got back noticed pool of fluid under one caliper..and reservoir was empty..loosened bleed screws completely and fluid started pumping through. Pushed the piston out so I can change seals. Must have been battling with air lock as you say.

yay, well done