Storage used for "/" showing 100%

[czonin5190]

• What Grafana version and what operating system are you using?
  Grafana Cloud, Ubuntu Server, docker

• What are you trying to achieve?
  Display proper storage usage

• How are you trying to achieve it?
  I set up everything using the instructions here: Monitoring a Linux host with Prometheus, Node Exporter, and Docker Compose | Grafana Cloud documentation

• What happened?
  I’m monitoring node_filesystem_avail_bytes which is showing the correct usage of my drive mounted in /mnt/md0, but for / it’s showing 0

If I use df -Th on my machine it shows / at 8% used

• What did you expect to happen?
  Correct storage metrics will be shown

• Can you copy/paste the configuration(s) that you are having problems with?
  Can post docker-compose.yaml and prometheus.yaml if needed

• Did you receive any errors in the Grafana UI or in related logs? If so, please tell us exactly what they were.
  None

• Did you follow any online instructions? If so, what is the URL?
  No