Disk/Filesystem metrics not visible (but all others are fine)

I’ve got a cluster with Prometheus installed (via Helm) as well as node-exporter and kube-state-metrics.

Lens is configured to read metrics from the prometheus service, and it’s happily displaying CPU, memory, network metrics.

However, viewing a node, the Disk tab says “Metrics not available at the moment”. Viewing a pod, the Filesystem tab graph is empty.

What am I doing wrong? What do I need to enable to read these metrics?
We are using the openebs-zfspv storageclass. Is this not compatible with reading disk usage metrics?

Any suggestions on how to resolve or investigate this would be appreciated. What metrics should i expect to see in the /metrics endpoint that correspond to disk usage?