Just because you encounter frost on the outside of a propane cylinder, does not mean the liquid propane inside the tank is not vaporizing and available for fuel.
In rural MN, those areas that are not served by Natural gas use Propane dispensed from tanks. These tanks are 500-1000 gal. tanks. Farmers use them for grain drying, heating outbuildings, and fuel for residential appliances. They are typically placed outdoors, above ground. I guess I'd ask itguy what he thinks all these folks do when the weather cools or demand is high from those tanks?
Regardless, it is not the issue of the OP.