How to troubleshoot a webhook that doesn't get called

I have a cluster on GKE where I’m trying to use Hashicorp Vault sidecar injector. I’m installing it with the Hashi helm chart with nearly all defaults. I had the configuration working in the past.

The sidecar injector works by implementing a mutating webhook in response to pod create/update events. Everything is healthy so the injector is ready to receive webhook events. But Kubernetes isn’t calling it. I looked over the MutatingWebhookConfiguration resource the hashi helm chart makes and it specifies what appears to be a correct configuration.

Is there a log on the kubernetes side where I can see reason for failure, assuming Kubernetes is trying to invoke the webhook and failing?