The pigtail has a shutoff valve in it that blocks the gas flow if you break the gas line. Opening the valve too quickly can also trigger this valve to close. A guy at a propane shop explained this to me and also said that you sometimes have to rap the pigtail against something to get the valve to reset. Usually this shows up as a NO GAS problem which is a little different that what you are describing. I'd suggest disconnecting the pigtail and rap it against the side of the tank a couple of times, reconnecting and opening the valve slowly and see if the problem goes away. I now have a "spare" pigtail that I bought trying to figure out my "no gas" problem.
2013 F-350 CC SB 2WD 6.7PS
2013 Eagle Premier 351 RLTS
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