To add to the data points:
I tried to apply for Amex Delta Gold and got the dreaded message saying I wasnt eligible for the sign up bonus.
I've only ever opened ONE amex card, the Hilton Aspire, this August, which is very much still open. No previous history with amex other than that.
I also used the card 2 weeks ago to pre-pay for a week of stay at the Hilton during December.
Any ideas of why I am not eligible for the signup bonus? Does Chase applications affect Amex?
I opened the Aspire in July and the Hyatt in Aug. Naturally, I stopped putting spend on my Aspire after Sept, as Im trying to meet the 6k on the Hyatt.