Aww, man, I wish I had seen this thread before you had to go through all this stress.
Yea, it's identity & address verification.
When I got my first card from AMEX about 1.5 years ago, I had just moved a couple months prior, so when I submitted my app online, it said I'd have to call in. When I did they said they needed to verify my info with me and confirm the new address popping up (like you, the address was never seen on my reports at that point).
I think reason my approval happened then & there on the phone was because it was only a rental property. You're probably getting tied up due to the recent mortgage craziness and verifying you're all good on that end. Maybe something like the process is too fresh in the system for your name to be appearing as owner of the new house. Figuring out your monthly mortgage payments & new DTI before giving a proper limit on the card. Yada, yada.
