The two previously posted pics clearly show a gap between the end of the stop screw and the stop.
Try removing the pivot pin from the clutch arm and slave's pushrod, and see if that allows free movement of the clutch arm. You may have to back off the stop screw a bit.
In an effort to keep the clutch arm as close to vertical (12 o'clock) as possible, you might try removing the jam nut on the slave's pushrod and screwing the two pieces of the pushrod together, bottoming one into the other, and tightening without a jam nut. This solved a similar issue that I had. You could also try using an actual (thin) jam nut.
YMMV
John