I have had AWS ACM certificates not auto renew and a couple of things could be the problem. For one maybe it’s DNS CNAME entries does not exist anymore. That is obvious but in my case these were certs that I do want to keep but they are not attached to another AWS service and that makes them not auto-renew and shows as ineligible in the console.
I am fixing this by making sure certificates are attached to something to avoid them becoming ineligible at auto renew time.
WARNING: Once failing to auto-renew and expired you have to issue a new one.