Perhaps a matter of semantics.
There are generators that tap liquid LP and then convert it to a gas/vapor with an in/on generator regulator.
These on-generator regulators (at least on the 6.5 KW Onans I am familiar with) can easily clog with the longer hydrocarbon "contaminants". I have overhauled them and it is not uncommon to find them half filled with a light viscosity grease-like substance.
The long-term solution (in addition to overhauling/replacing the regulator) is to switch from the liquid tap to HIGH PRESSURE vapor (i.e. before the house regulator). Only potential issue is icing at cold temperatures/small tank.