I believe there was also a recent entry about fuel venting (although I can't remember which side).
That would open up a whole new can of worms!
Fuel venting: most common cause, a failed vent valve.
But would be interesting to know if the imbalance was causing an INCREASE in another tanks qty. This would have to be a failure (internal leak) of 2 valves, a jettison transfer valve and a refuel valve. (Or a split manifold!)
However back to the original defect. As already posted in order to get the pressure switches made in both O/Jett pumps then BOTH pumps would have to have a failed NRV.
Interesting one that!