Never heard of this failure either!
On my ICE BMW, the pump runs in two directions (relay-controlled). FWD directs water to the windshield, REV directs water to the rear window.
With the hood open, have someone sit in the driver's seat and call for water at the windshield and then the rear hatch. Regardless of whether you get spray or not, can you hear the pump run? If yes, then the water lines may be blocked or cracked (and leaking).
If you can't hear the pump run, locate the pump, disconnect it electrically, and check the harness pins with a multimeter while someone again sits in the driver's seat and calls for water.
If you have voltage changes then that indicates a pump motor failure. In my ICE BMW it's an easy replacement: drain the reservoir, remove it from the car, and pull the pump (it's friction-fitted into an opening in the reservoir).
If you don't see any voltage change at the harness (and are sure you're checking the right pins) then it could be the stalk switch, control module, or a wiring break somewhere.
Let us know what happens!