VmPro will report an alert if it discovers any VMs with independent flag on its disk, any VM with physical RDM disk or any VM with bus sharing (clustered) disk.
If the disk does not fall into the above list then try to rediscover the VM. Select the VM via the vmPro GUI under the VMs tab and then edit. Disable export, CBT (if using), and VSS (if using) and then save. Select the VM again, edit and just enable export, save and then run a backup, if successful edit once again and have Export and CBT enabled and run a backup. You can do the same with VSS if your are needing to use VSS.