Originally Posted by
skywardhunter
When you upgraded your ticket was reissued and at that point the earlier flight may no longer have been available (or not available in J).
There are minimum fare requirements for DC, too
I guess it is possible that the earlier flight did not have any J availability; didn't check.
update: Actually now that I think about it, pretty sure the day of/day before my upgrade was processed, EF showed saver award space for the flight before and after mine