The following critical alert is displayed when backing up Hyper-V host and virtual machine(s) on it:
The running backup has not shown any progress for some time and may be frozen
Most likely cause for this alert is that VM backup is queued as it is waiting for host backup to be completed.
Error message text will be improved in the future product releases.
To avoid queued tasks in such cases, make sure host and VM(s) are backed up at different time:
1. Do not schedule host and VMs backup at the same time;
2. Do not back up host and VMs in the same backup plan;
If other tasks are completed, but alert is still generated and backup activity is not running, it may be caused by a lockup. Troubleshoot as per Acronis Software: Troubleshooting Application Lockups