Um, no!
If I buy $x of gift cards, that's because I want to push $x thru my AmEx Edge into gift cards which then in turn gets pushed into ATO / strata / Service NSW / insert anything here.
If I am entitled to push $250 x 5 into ATO via AmEx Edge, but I only push thru $250 x 3, then I would be pushing the balance of $250 x 2 via some other method, which earns me less or no points. I would be losing $250 x 2 of AmEx Edge points.
Bad outcome!
Normally, you scan all the cards, scan FlyBuys, insert your AmEx Edge to pay, AmEx approve, then the cash register would activate each gift card, then the receipt would be printed with:
xx_xx 3rd party gift card $257 approved
xx_xx 3rd party gift card $257 approved
xx_xx 3rd party gift card $257 approved
xx_xx 3rd party gift card $257 approved
xx_xx 3rd party gift card $257 approved
xx_xx American Express $1285 approved
Today, no.
Scanned all the gift cards, scanned Flybuys, insert AmEx Edge, AmEx Edge approved.
Then cash register would pop up saying activating.
Then cash register would pop up saying to the effected of (can't remember exact to the words, but keywords were) "Card xx_x could not be activated, please follow refund process"
The cash register would stop here.
So I got the staff, they noted down the gift card number on screen, dismissed the pop up message. Cash register would continue, until it's done.
It would print out a receipt, and the first receipt says:
xx_xx 3rd party gift card $257 declined
xx_xx 3rd party gift card $257 approved
xx_xx 3rd party gift card $257 approved
xx_xx 3rd party gift card $257 approved
xx_xx 3rd party gift card $257 approved
xx_xx American Express $1285 approved
In this order.
And of course, the receipt from my second purchase was
xx_xx 3rd party gift card $257 approved
xx_xx 3rd party gift card $257 approved
xx_xx 3rd party gift card $257 declined
xx_xx 3rd party gift card $257 declined
xx_xx 3rd party gift card $257 declined
xx_xx American Express $1285 approved
At the first store, the staff brought up the original sale at the service desk, scanned the 'declined' gift card, got me to present my AmEx, and $257 was refunded to my AmEx. I then went to the shelf, got another $250 card, and then went thru.
At the second store, the staff brought up the original sale on the service desk, just like the first store did, scanned the declined gift cards, then they just did a cash refund and the cash register allowed it! They took out a stack of $50 then started counting

I was like "Are you trying to give me a cash refund?" They went "Yeah". So I said "Don't need to count, I want to buy 3 more because these 3 didn't work, so you don't need to give me the cash, just push it thru. They went "OK". I guess I should have taken the cash, and pay with AmEx again, hey?
You should pay attention, you are not buying $2.5 mangos!