You have a LEAK downstream of the LP Switch so it's not on tank fittings.
Regulator has 2 vents..........small pin hole on 1st stage (high pressure side) and a larger screened one on 2nd stage (low pressure side). They leak if diaphragms are bad.
Otherwise......the leak is in a fitting, hole rubbed in line, gas valve leaking thru on furnace/water heater/fridge/stove-oven.
You can hear flow but can't smell it.........no LP alarm from detector so it must be exterior. Check under/around rig.
Might try using a long BBQ lighter and see if you can light main flame on fridge/water heater/furnace with them OFF. If their gas valve is leaking thru you will get a small flame
Might need to take to RV Bulk Distributor and have them us electronic leak detector to pin point area/source of leak.
You have a LEAK!