Secret won't mount for Azure AKS - Unable to attach or mount volumes - thoughts?

[blue928]

I'm following the tutorial for Azure located at: https://github.com/kubernetes-sigs/external-dns/blob/master/docs/tutorials/azure.md

I'm following the instructions precisely for both Managed Identity and Service Principal. No matter what I try, I cannot get the secret to mount.

I apply the secret with kubectl create secret generic azure-config-file --from-file=/local/path/to/azure.json and kubectl get secrets shows that it's there.

After a few minutes kubectl describe pods shows the following events:

Type     Reason       Age                    From     Message
 ----     ------       ----                   ----     -------
 Warning  FailedMount  24m (x104 over 16h)    kubelet  Unable to attach or mount volumes: unmounted volumes=[azure-config-file], unattached volumes=[kube-api-access-n4rxx azure-config-file]: timed out waiting for the condition
 Warning  FailedMount  9m31s (x478 over 16h)  kubelet  MountVolume.SetUp failed for volume "azure-config-file" : references non-existent secret key: externaldns-config.json
 Warning  FailedMount  3m47s (x326 over 16h)  kubelet  Unable to attach or mount volumes: unmounted volumes=[azure-config-file], unattached volumes=[azure-config-file kube-api-access-n4rxx]: timed out waiting for the condition

Thoughts on what I could be doing wrong? RBAC is enabled, so I'm just copying and pasting the externaldns.yaml file from the tutorial.