It happened to me a few months ago. I took screen shots of the upgrade list with my name at the top as well as the seat map of the FC cabin showing one seat open and filed a complaint online. Six weeks (months?) later I received an email response with an apology and a promise that 8,000 miles would be added to my SkyMiles account within three business days. The email was sent November 1, but I still haven't seen any miles credited.

I can only surmise that a Delta 'business day' is based on the rotation of Venus, where a single 'day' is 5,832 hours.