I am using stable/prometheus-operator for monitoring kubernetes cluster. But the disk metrics are showing zero for all the pods. Is there anything to be done to resolve this. cadvisor end point is active in prometheus

Service monitor configuration

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  creationTimestamp: '2019-10-24T06:40:18Z'
  generation: 1
  labels:
    app: prometheus-operator-kubelet
    chart: prometheus-operator-6.18.0
    heritage: Tiller
    release: prometheus
  name: prometheus-prometheus-oper-kubelet
  namespace: default
  resourceVersion: '2595'
  selfLink: >-
    /apis/monitoring.coreos.com/v1/namespaces/default/servicemonitors/prometheus-prometheus-oper-kubelet
  uid: 5039932b-3224-4c24-ae13-d9a2b540c02b
spec:
  endpoints:
    - bearerTokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
      honorLabels: true
      port: https-metrics
      scheme: https
      tlsConfig:
        caFile: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
        insecureSkipVerify: true
    - bearerTokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
      honorLabels: true
      path: /metrics/cadvisor
      port: https-metrics
      scheme: https
      tlsConfig:
        caFile: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
        insecureSkipVerify: true
  jobLabel: k8s-app
  namespaceSelector:
    matchNames:
      - kube-system
  selector:
    matchLabels:
      k8s-app: kubelet