Got it sorted, thanks for the motivation. Today's initial agent said the same thing, no upgrade space available. I mentioned that I saw 5 seats open still in Z class and so he contacted the Global Partner desk. 20 minutes on hold while worked with them and he came band on and said that they didn't see any upgrade either, but then they went into Korean's system and saw the Z seats showing there (so I guess Delta's system didn't match the partner availability that Korean's system showed). Another ten minutes and they got it sorted and now i show flying on a Korean flight number on the Delta app and in Prestige on the A388. Now just fingers cross that work doesn't change my travel days between now and November. . I have a feeling undoing all of this will be a pain!