Just thought I would post this here as another data point.

The last two itineraries I have flown have had this exact same problem. I booked on Delta.com, made sure that "Request Upgrade" was checked, and checked that it was showing "Upgrade Requested" on My Trips. I am Silver Medallion so I don't check back for the upgrade until 1 day before the trip.

Both times, I check back at Delta.com to see that the flight is now showing "Upgrade Eligible" instead of "Upgrade Requested". EF shows V4 so I know there is inventory available. I call Reservations and ask why I am not on the upgrade list (today, the agent actually insisted that I must be on the list and just hadn't cleared because I was Silver ; I asked him to check "just to be sure" and of course EF was right and he was wrong). Both times the Res agent was surprised to find that I have, in their words, "declined the upgrade". Both times, I inform them that it is not true, and ask to be reinstated. Both times, the upgrade immediately clears.