Just a suggestion.
Have you tried bleeding the wheel cylinders
at the line instead of the bleeder screw to see if the wheel cylinder is full of (Crud)?
Over time these line nuts get rounded when care is not taken to loosen them or someone grabs a pair of vice grips to loosen it.
Most auto stores have brake line wrenchs.
Here is a link.
Link:
https://shop.advanceautoparts.com/p/...h+Set+standard
.