Yes, either the new Master Cylinder is defective or you still have air in the lines.

Bleed the brakes uses a line into a glass of brake fluid so that no air can be sucked back in. Bleed the left rear wheel first, the right rear. Then do the left front and finally right front.

Do not forget to manually adjust the rear brakes by turning the 1/4" stud.

BTW, B210 has no proportioning valve, but it does have a splitter with built-in pressure sensor.