Booked this flight on a MileagePlus ticket. I have since determined that it is no longer bookable on SQ in any class of service but 1K desk says it’s still flying and hasn’t been canceled. Do you guys think:

A) UA 1K desk is correct that it is still flying and not to worry.

B) SQ has already canceled it and it doesn’t flow into MileagePlus system. Reason why? Data source?

C) SQ has the flight in a sort of purgatory and it will soon be canceled. Data source?

D) Something else. Data source?

If B or C, I’d rather rebook it now and get a good seat and amend my plans early rather than wait for the IT of the airlines to serve the customer well.