Acronis Backup: Backup of a Linux machine fails with "No volumes have been found while processing the template"

Symptoms

1. You make an entire machine backup or disks/volumes backup of a machine with Agent for Linux
2. Backup fails with the following error:

   No volumes have been found while processing the 'All Volumes' template.

   or

   No volumes have been found while processing the 'Fixed Volumes' template.