Step 12. Specify Guest OS Credentials for Microsoft Hyper-V VMs

After you upgrade to Veeam ONE 12.3 (build #12.3.0.4670), you must specify credentials of an account that will be used to collect data from Windows guest OSes on Microsoft Hyper-V VMs. If you do not specify guest OS credentials, Veeam ONE will not display guest OS data (in particular, data about guest disks) in monitoring dashboards, alarms and reports.

For details, see Step 6. Specify VM Guest OS Credentials.