NetBackup character restrictions for vhd or vhdx names and the VM path when the Enable file recovery from VM backup option is used
For Hyper-V policies that include the option, non-ASCII characters are not supported in the vhd name or vhdx name or anywhere in the VM's path. Examples of non-ASCII characters are Japanese or Chinese characters (multi-byte). If the virtual disk name or VM path contains non-ASCII characters, the backup job completes but the VM's files cannot be individually restored from the backup.
As an alternative, you can restore the entire VM.