Do you think, maybe heavy fusel oils remaining in the still migrated into the tobacco? If so, maybe package it in charcoal and baking soda for a bit.
I know my friend threw paint brushes in the freezer and after a while everything that wasn't stored in glass in the fridge part was garbage. Those heavy hydrocarbons permeate everything. It took a couple months of baking soda treatments to clear the fridge of the aroma.
I have no doubt they also are absorbed into the walls of the still and any fittings and hoses. At work I've been in plenty of vessels that have been steamed, and air tested, yet still have a smell.
One time I was in a stainless steel clad train car, and it was so strong, the air test card at the entrance said, "don't worry about the smell, it's just the acid." Anyways, on a microscopic level metals are porous.