just reading the bug notes of OP, the cause seems to pretty clearly be that the sbackup doesn't mount smb share if it's not already mounted; definitely sounds like wishlist as per OP sbackup automated backup works if share is mounted.
possible fixes would be to modify the cron-job for scheduled backups to mount the smb share, or mount it at boot via cifs in /etc/fstab.
wishlist item would be to add a feature to sbackup to check prior to backing up and mount the designated location if not already mounted.
just reading the bug notes of OP, the cause seems to pretty clearly be that the sbackup doesn't mount smb share if it's not already mounted; definitely sounds like wishlist as per OP sbackup automated backup works if share is mounted.
possible fixes would be to modify the cron-job for scheduled backups to mount the smb share, or mount it at boot via cifs in /etc/fstab.
wishlist item would be to add a feature to sbackup to check prior to backing up and mount the designated location if not already mounted.