My guess is they cashed and used your check for their next bag of groceries. When enough customers get unhappy, checks dry up , they run low on groceries, service improves, and production and deliveries ramp up, is my guess. From observing over the years, they seem very cyclical in terms of performance.
Financial wizards able to make bucks off unfulfilled but paid up orders? Well, I doubt that very much.
Still, I have yet to see a post where a customer says he never got his product. (And if you've only been waitin' a year or so, give it another 18 months...

)