You store backups on an SMBv2 network share. You use a Linux Agent to browse backups (Web console -> Backups).
You notice, that backups of 'version 12' format are not listed.
Issue in the CIFS implementation in Linux, see Bug 13334. The issue occures only if the whole destination disk is shared.
As workaround, create a folder on the destination disk and share this folder. Save backups to this shared folder.