Business card applications are evaluated based on the creditworthiness of the individual, because the individual (not the business) is the applicant. I don't think having a promo code will affect American Express's decision to extend credit, but I have no direct experience with the specific circumstance. I assume you do have a Social Security number and some type of USA credit history will all three bureaus?
Yes but I have one began building it a few months ago. On Discover it still shows my Fico score as "unavailable" even though I'm on my 4th billing cycle. Is that normal?