If you got the rear drums off ... GENTLY press the pedal to check for movement on the bad side. You looked INSIDE the grommet (by lifting the rubber with a screwdriver) did you?

Check bleed that side. Make sure the resevoir is full, and give it a few rapid presses, then bleed normally.

Do you have limiting valve assy under the bonnet in the brake lines?

Back later .. sorry gotta be out.