Your older RV with the shut off solenoid is not like the newer RV's built to the newest RV code.
To get you going now, and till or if you want to find and replace the old parts. Know that you can shut off the tank, and remove either the solenoid plunger, or the whole solenoid system, open the tank and check for leaks.
You can source parts from marine supply stores, or West Marine, as the yachting world does still install solenoid propane shut offs for safety.
I removed the one in my 93, but my 98 never had one installed. Do whatever makes you happy.
Dave and Dolly
1998, 36' Foretravel, U295, rare mid door
2001 Jeep Grand Cherokee