I previously forgot to pay a $175 monthly bill on my AMEX Green. I paid it on the second day after the due date. But then a notice showed up in the Membership Rewards Summary saying that 175 points were eligible for reinstatement.
AMEX is actually pretty sneaky about this now. If you have not paid your bill yet, it will lock the MR points earned from that billing period so you cannot access them. If you miss the due date, those points will be taken away directly. That portion of the points can be restored, but only by paying for them. Click “reinstate points” and you will see the screen. No matter how many points are involved, it costs $35 to reinstate them, which is quite expensive! Of course, for my 175 points, I just let them go.
Let this be a lesson for everyone: always pay your bill on time~!