Pretty sure I'm in this jail too. What's weird is that I've literally only had 2 Amex cards - the free Hilton one (gotten 3 years ago) and the Personal Plat (got it last year). I primarily use my CSP though, so maybe that's why? Either way I've gotten the ineligible pop up both when trying to apply for another Hilton card OR the Marriott card, so it's across the board. Guess I'll use the plat a bit more often before I cancel it and make sure to remember to use the free card at least once a month until I'm back in the good graces?