Had the same problem with our 2015 Flaffstaff 8528RKWS. What I found was that on the Fairview regulator there are two brass couplings that are actually check valves. they are located one on each side of the crossover Fairview valve. Inside the brass check valves there is a spring and black plastic disk. In one of mine the disk was stuck and it would not allow gas to pass through. The brass coupling is known as a "Inverted Flare to MPT Connector" 1/4 Inverted Flare X 1/4 MPT. Part number 07-30045 JR Products, www.jrproducts.net
. I replaced the bad coupling and all was well.