Active Paid Users Showing as Expired in Amember

A client just reported yesterday they were unable to access their subscription in WP site. When amember was checked, I see the problem is widespread with only a couple of paying users still showing as Active. All the rest are showing as Expired even though I have verified with the payment gateway that payments went through ok. I have another client who successfully renewed their membership a couple of days ago so this one person plus another who signed up through paypal are ok and everyone else cannot access their membership material.

Any ideas on what has gone wrong?

Thanks.