You aren't getting membership rewards points from the Costco/Amex True Earnings card. If you have any membership rewards points, they are from a different Amex card.
BigDaddy18: If you want to earn Amex membership rewards cards for Costco spend, just use an Amex that gives you membership rewards points when you check out. They take any Amex card. You don't have to use the Costco Amex card at Costco when checking out. And since it's easy to beat the 1% rebate you get at Costco on that card, you are probably better off using a different card.
-David