Further data:
The tanks are from either Manchester (US-made) or another mfr. None are exchange service, I purchased them new. One is less than one year old, others range from 1 to 5 years old. All work with other appliances (grille and fire ring) both before and after testing with 1# adapter.
I have two adapter hoses, one with an Acme (right-hand thread connector) and the other with an old-style POL nut connector (left hand thread), and neither work on any appliance on any tank.
I've tried turning on the tank slowly. No difference. The tank and appliance connectors are as tight as I can make them. I know about the protection valve in the tank valve, someone triggered one when they tried to drain my propane tank when it was on the trailer over night. The easiest way to reset it is to just slowly screw in a POL fitting, it pushes the valve back into it's correct position.
I have filled out the "Support Request" form on the Mr. Heater web page but haven't heard from them. They don't list hoses and adapters on the support site product pick list, so I don't know if they saw it.
<Chas>
