Nope postpaid, but it is a dealer account from my work.
Ah so it is billed, but not to your name. That might be the issue.
This verification is for your own protection. Citi is looking out for you.
Once you close the loop on verification, things should be better. Hopefully that verification is just the one letter.
When did you last change where you live?
This looks like your first Citi card, or is your Siggy incomplete?
Citi is looking out for Citi. The consumer isn't responsible for fraudulent activity on a card if the consumer had nothing to do with it. And if Citi can't get their money back then Citi is on the hook for the loss. Inconvenience for you is much better for Citi than lost income and theft.
Interestingly enough, the only card I've ever had hacked is my Citi Premier. I never got flagged before the hack and have never been flagged since. I have multiple Citi products with multiple authorized users.