Try gently disconnecting the wiring connector under a somewhat large rubber boot in the front doors and check for continuity/contact corrosion on pins 13 and 14. If it's any help, the driver side windows wires have violet and black insulation, while the passenger side are violet/gray and black/gray.
I had the exact opposite issue (fronts OK, rears kaput) that was cured by swapping in two salvage yard harnesses. FWIW, the connectors for the rear door harnesses are in the B-pillar under the long trim panel.
Good luck with it.