I had been receiving a CC-502 with Citi (Costco Visa) for some time, and was waiting to go through my receipts to verify downloaded transactions before it would allow me to deactivate/reactivate, to fix.
Today, I'm instead getting the CC-503 error with Citi, though my login information is unchanged, and should be correct in the vault. I see no announcements about this (I see CC-502 announcement for Citi, last updated in January).
I'm on WIndows 10, and Quicken R49.33/27.1.49.33