Hyper-V 2012 R2 virtual machines may be in the Off state when restored
This topic applies to the NetBackup Hyper-V VSS backup method only (not to WMI).
For Hyper-V server 2012 R2 and later, the virtual machine is restored in the Off state (not the Saved state) in either of the following cases:
The virtual machine's operating system does not support Windows Volume Shadow Copy Service (VSS).
The virtual machine does not have Hyper-V integration services enabled.
During the backup, the virtual machine is not placed in the Saved state (the bin file and vsv file are not generated or backed up). The Hyper-V VSS writer instead creates a checkpoint of the virtual machine. As a result, the virtual machine remains in the Off state when it is restored.
The following MSDN article contains more information:
Hyper-V Backup doesn't interrupt running virtual machines (anymore)