Flavored coffee is sprayed with flavoring after roasting. The solvent that carries the flavor is not listed on the ingredient statement.
Dunkin' French Vanilla reads coffee, natural and artificial flavor. New England Hazelnut Creme reads 100% Arabica coffee, natural and artificial flavors. Community Pecan Praline, same two lines. What those lines leave out is the spray. The roasted beans tumble in a mixer while liquid flavor gets sprayed on, about 3 pounds of flavor for every 100 pounds of coffee, and that liquid is mostly propylene glycol, a synthetic solvent that carries the flavor oils on to the bean. A supplier's spec sheet for a pecan coffee flavor reads propylene glycol and natural and artificial flavor, use at 3%.
It stays off the bag because FDA treats the solvent inside a flavor as part of the flavor. Food grade propylene glycol is allowed in flavorings up to 97%, FDA lists it as safe, and a small amount is used.
A few roasters flavor with alcohol or glycerin instead and print no propylene glycol on the bag.