One of my valves (between the tank and the pump) tends to stick, and when it does the lever will move, but the valve internals don't. it sounds like that might be your problem: the lever has come loose and is not actually turning the internal ball valve?
Adam and Sue, and a pack of little furballs
2007 Holiday Rambler Endeavor 40PDQ Limited Edition - Cummins ISL 400
2013 Ford F-150 FX4 toad - USGear Unified Tow Brake, Roadmaster Blackhawk II Tow bar, Blue Ox baseplate
Home base near Buffalo NY, often on the road to a dog show