What wheel cylinders?

Hmmmm.... I really have to suspect that things are not all kosher up front. Everything clean? Front bleeders at the top of the calipers?

Maybe do the 'gusher' test that some here have described so well..... take the cover off of the MC, press the pedal really hard and then let up slowly and look for a gush of fluid up out of the rear MC reservoir. (As a precaution, cover the area with a couple of layers of cloth to catch any fluid spills.) A gusher indicates air in the half of the system where the gusher comes back.