Originally Posted by
Bowgie
OP says the fare code for the missing flight was booked as X, but later changed to R. Maybe Delta's system thinks the segment is an award flight?
...which of course it can't be - you can't have a single PNR/ticket that is revenue in one direction and skymiles in the other direction - such a ticket is simply impossible. DL needs to fix this - just keep reaching out to DL until you find that proverbial agent who understands the big picture.