Propane not working in stove

With propane vavled in service and NO propane appliance turned on the Main LP Reg goes into 'lockup' to keep system pressure in check.

When turning on a propane applinace the REG has to establish flow and control system pressure which is only 0.4psi so it can take awhile
Stove top/oven has it's own LP Reg under the burner top. It also has to estalish flow/pressure which is dependent on Main LP System pressure
Stove/oven LP Reg controls at 10"WC (0.36psi)

Usually lighting off stove top burners on HIGH will add in placing Main LP Reg in service and therefore stove/oven reg in service.
Use a lit match held at burner...turn burner on HIGH and WAIT.....burner will light off when System pressures/flows have been established.

Furnace is biggest demand on LP System and that is helping to establish flow/system pressure
All Stove top burners on high 2nd highest demand
Water heater...3rd
Fridge burner ----lowest demand

Main LP REG
Lever....left right center??
Frist cylinder valved in is primary ....turn lever towards that cylinder
Second cylinder valved in is secondary .....when 1st cylinder pressure drops to ~10psi the auto changeover port will swap to secondary cylinder and indicator will go RED. Turn lever towards secondary cylinder and indicator goes GREEN. Valve out 1st cylinder/remove-refill and then place back in service (open valve slowly)--it is not secondary supply -----repeat as necessary

Always Open the cylinder service valves SLOWLY...should hear a CLICK then fully open the valve
Opening too quickly can cause Excess Flow Device to trip (Inside the BIg Green ACME Nut) ---Close valve wait 30 seconds then open SLOWLY to reset

You're purging the lines first, and then it still won't light? The furnace has zero to do with the stove, except before where the propane line tees off.