Rear line bleeding/ prop valve clogged?.

The rubber hoses do sometimes collapse inside and block fluid flow, no insect req'd. And just due to the rash of related threads recently,,, check the pushrod / master cylinder travel. The brake lamp switch adjustment can prevent master cylinders full return. This usually results with brakes held on/dragging. I don't know what effect it might have in the bleeding process.
Some of the OEM type proportion valves are a pain to get centered so fluid flows both ways and the warning lamp stays off. The cast iron one with a tiny button stem thingy at one end? I forget. Anyway... There was a thread where someone said old school method, kick/stomp the chit outa the pedal would fix it. That's all I got. Hope it helps.