this has happened to me twice now, and the worrying thing is that CX have no idea what's going on.
Basically i upgraded form Y+ to J (post dec 5). miles were deducted and all looked good except i could t check in online. The system said it could find my ticket, but it still appeared in my itinerary's.
When i got to airport they had no booking in my name. took many calls and searching for them to find the tix and put them into the check in system.

so it meant i couldn't check in online, and also that my assigned seat was given away.
very annoying and as i said CX have no idea what is going on.

flights were SFO-HKG and HKG-SYD

anyone else experiecne this?