i noticed something today i discovered by mistake..

yesterday i added 4 $200 amex giftcards to my amazon payment account so i can drain them.. i expected a $1 temp charge like always.. today i made 4 $150 transfers and one fails.. i check the balance on that one card and it does not show the $1 temp charge where all the other cards do.. i go to my cards in amazon and hit edit card.. i noticed right off the exp year show 2019 not 2020.. so it lets me fix it.. i check the balance and there is still no temp charge.. i send payment for 100% of the value of the card and it clears.. might only work with amex but it seems really useful..