I used my HH Amex last week to pay a $2,285 payment on PayPal and it was declined. I finally realized that it was probably Amex causing it. I say that because the PayPal site crashed about 12 times in the process and it was hard to tell if it was them or Amex. The Amex phone rep said she could fix it in about 5 min. and to try again then. I couldn't wait and had to try later that evening and had to call Amex again. They fixed it right away. The first call seemed to be in India and the second sounded American.

Finally got it done, but between the crashing PayPal site and Amex blocking it was pretty frustrating. Note that my Visa was also blocked a few times when purchasing Charter One gift cards ($5,000) and the csrs at VISA would release the cards instantly also.