UrBackup backing up 2 drives but not the third

I have a farm of 20 Servers all being backed up using UrBackup. All Disks on all VM’s are backed up once a week with 1 exception. Each VM has 2 or 3 disks.

I have 1 VM with 3 disk but only 2 ever get backed up. The SQL Data disk gets ‘skipped’ or just not backed up every time the backup runs.

I’ve tried the following to resolve :-

  1. Deleted the VM from the UrBackup server and recreated it and the client
  2. Reinstalled the Client on the VM
  3. Manually selected the Drives to be backed up

Is there a setting on the drive that could be preventing UrBackup from backing this disk up ?

Feels like this is an easy fix but I just can’t see it

All help appreciated.