Backup of Hyper-V VM (VHDX format)

Hi,

Environment:

 -BE 2012 R2 SP3 Server with 4,5 TB B2D device.
- VM on Hyper-V 2012 with three VHDX files (2x 50 GB, 1x 100 GB)

This VM has suddenly the error message "V-79-57344-38721 - Failed to mount one or more virtual disk images"

If I backup VMs with VHDX volumes, must the B2D device formatted with 4K sector size ?
In this MS article (http://support.microsoft.com/kb/2510009/en-us) I can't see that this apply
to Backup Exec.

regards
Dirk Ehlers