First one I ever used was a measly spend $5 at Dunkin Donuts and get $5 ... Usually prefer Starbucks coffee or Mcdonalds but Spending $0.10 on Coffee too good to pass up after getting a Large Ice coffee and a bottle of Soda for somebody 
Most of those offers are local stuff that I don't care about 
Got the credit posted instantly - same time the actual charge got posted to my account.
Even though the product wasn't actually sold by amazon.
I made a gift card purchase for 20$ and received a msg from Amex app saying "thanks for using your enrolled card..." instantly so hopefully I'll be seeing that 20$ credit soon
@xerostatus wrote:This is what I learned from my recent experience:
I had the "buy $20 or more on amazon, get $20 back" deal.
So i went online and happily made my purchase (it was well over $20, around $40 actually).
Waited and waited, but no credit. I've done these amex deals before, and its actually very quick turnaround.
So I knew something was up.
Found out that only purchases made DIRECTLY to amazon.com is eligible.
Which is fine, by my books, but it would be better if Amex directly told you this upfront.
Their terms/conditions of the deal is in no way clear, and even asking their CSRs is of virtually no help.
Based on my experience, if your amazon purchase is made to one of those third-parties who simply sell using amazon, it is NOT eligible.
It has to be direct to amazon, as in, amazon itself is selling you this particular product.
If you make a purchase to a thirdparty, your transaction will look like:
"AMAZON MKTPLACE PMTSAMZN.COM/BILL WA"
This would NOT be eligible for the deal/promotion/w.e
If you make a direct purchase to amazon.com, it would look like:
"AMAZON.COM AMZN.COM/BILL WA"
And this purchase WOULD be eligible.
If you make an eligible purchase, you should see the credit back withi 1-2 days of the eligible transaction posting.
Now, easy way to avoid all this confusion? Just buy an amazon.com e-giftcard for the amount which your deal is for.
That purchase would indeed be directly to amazon.com and be eligible for the credit back promotion.
Then you can use that e-giftcard to make any purchase, third party or direct to amazon, doesn't matter since you've already locked in your credit back through the initial giftcard purchase.
I actually had the opposite experience with this just recently. I would definitely suggest reading the terms included on the offer - mine said that it would apply to any purchase either directly listed by Amazon OR fulfilled by Amazon (which my purchase was a third party, but fulfilled & shipped via Amazon). Just checked and my transaction was billed as "AMAZON MKTPLACE PMTSAMZN.COM/BILL WA" and my $20 credit was posted the next day (I didn't even click the redeem button! It just automatically went through for some reason.. no complaints here 
)
No AmEx Amazon.com offer for me!