Additional drive not mounting

I’m running RancherOS 1.4.0

I can’t seem to get my additional drive to mount using cloud-config.yml:

#cloud-config
mounts:
- - /dev/sdb1
  - /media2
  - xfs
  - ""
rancher:
  network:
    dns:
      nameservers:
      - 8.8.8.8
      - 8.8.4.4

I can mount these manually with mount /dev/sdb1 /media2 and it mounts without issue. What exactly have I done wrong here?

I followed the exact format in this article:
https://rancher.com/docs/os/v1.2/en/storage/additional-mounts/

ros config set mounts '[["/dev/sdb1","/media2","xfs",""]]'

If anyone can shed any light it would be much appreciated.