I think an additional thread solely for this topic is beneficial. There is a separate thread for this issue on Dan's Deals and on Reddit.
Amex Offers are joint ventures between merchants and American Express. The decision to claw back is certainly a joint one. Some are speculating that Staples is refusing to pay out because Amex failed to limit to one per person. However, Amex could contest this, or eat the loss. For example, there were several companies that went bankrupt where Newegg advertised their mail-in rebates, and Newegg offered gift cards for the amounts of the rebate as a courtesy.
As for the canceled online orders of GCs if paid with Amex, while this is true, to my knowledge there was no memo to stores to prevent in-store purchases. I and others had no problems purchasing Visa GCs with our Amex cards at B&M stores. Of course, many of us did this without waiting for a discount offer, paying $34.75 in fees per $1,000, which means we may now be losing money due to the $100 credits being reversed.
Here are the offer terms. One item that is clear now is that a "Card Member" is a customer of American Express. Even if you have 5 different cards with them, you are limited to $100 of total credits across all these cards. Additional cardmembers can receive up to $100 each, however (across all cards they have with Amex).
Must first
add offer to Card and then use same Card to redeem. Only U.S.-issued American Express® Business Cards are eligible to enroll. Your enrollment of an eligible American Express Card for this offer extends
only to that Card. Limit of $100 in total statement credits per American Express® Card Member. Offer valid in-store, via the Staples mobile app and online at Staples.com. Valid at participating locations in US. Not valid on purchases shipped outside of the US. Valid on US website only. Excludes Quill, Smilemaker, Staples Business Advantage, Staples 4 Government, Staples Toner Services, Staples Technology Solutions, Staples Promotional Products, Staples Print Solutions, Copy and Printing Services, Staples Contract and Commercial, Staples App Center, Staples Industrial, Staples Book Rental, Staples Simplexity, Staples Share Fund, Coastwide Labs, Catalog and Staples Fundraising.
Not valid for gift cards in bulk purchases. Offer is non-transferable. Statement credit will appear on your billing statement within 90 days after 11/30/18, provided that American Express receives information from the merchant about your qualifying purchase. Note that American Express may not receive information about your qualifying purchase from merchant until all items from your qualifying purchase have been provided/shipped by merchant.
Statement credit may be reversed if qualifying purchase is returned/cancelled. If American Express does not receive information that identifies your transaction as qualifying for the offer, you will not receive the statement credit. For example, your transaction will not qualify if it is not made directly with the merchant. In addition, in most cases, you may not receive the statement credit if your transaction is made with an electronic wallet or through a third party or if the merchant uses a mobile or wireless card reader to process it. By adding an offer to a Card, you agree that American Express may send you communications about the offer. POID: GB5E:0001
Notes: When the offer could be added to personal cards, it still said it was only for Business Cards. $100 credits were still received (and now reversed). "Bulk purchases" of gift cards are not something any of us were doing, as Staples has a separate program for events such as corporate raffles.