Acronis Backup: differential backup archives are not deleted from storage if cleanup by number of backups is used

Symptoms

1. You create a plan to backup disks/partitions with the following parameters:
   • Backup format: Version 12 (.tibx)
   • Where to backup: internal or external disk
   • Backup scheme: full backup + differential backups
   • Cleanup: by number of backups (e.g. maximum number of backups= 3)
2. You run the backup task several times;