[StaffsLUG General] Kubernetes/cert-manager

Hi All, Does anybody here have any experience with Kubernetes? I'm being asked to solve an issue with a kubernetes-based web portal not renewing its SSL certificates automatically anymore. I've been able to ascertain that it's using cert-manager with let's encrypt. I can also see that the cert-manager, cainjector and webhook pods are running... I've not used cert-manager before and I'm just wondering what else I can check? I've had a look on Google and the best I could find was to try and 'describe' the certificate and check the orders/challenges... but I don't know the name of the certificate and I can't even figure out how to list them. Kind regards, Adam P.S. If you're clued up on Kubernetes and up for a quick phone call, that would be amazing.