Were you expecting the invitation, had you been working with someone at American Express? They certainly should have known your FICO score beforehand, and could have seen the debt if it reported by a credit card issuer or another bank. Did your FICO score decline substantially in, say, the last 30 days?
I worked with my local amex rep and yes I was waiting for the invitation since last year. I just called the team and they told me they still reviewing my applicationI. have no idea what's happening now .