Failed to open Item

Acronis True Image 14 in Windows 8.1
Twice in a row this happened:
1. Used GroverH's excellent instructions to make a full backup to an external encrypted hdd
2. Backup completed normally, but at the end Acronis flashes the error popup:
"Failed to open Item"
3. Double clicking on the backup opens it normally and all seems fine
4. Attempt to mount backup from within Acronis fails: cannot find version 1

Should I just give up on Acronis? Please help.