Comment # 13 on bug 845589 from Michael Friesenegger

I believe I have found a similar issue.

The partitioning on my primary HD looks like:

# parted /dev/sda print
Model: ATA OCZ-VERTEX4 (scsi)
Disk /dev/sda: 256GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt_sync_mbr

Number  Start   End     Size    File system  Name     Flags
 1      1049kB  2500MB  2499MB  ext3         primary  boot, legacy_boot
 2      2500MB  32.5GB  30.0GB  ext4         primary
 3      32.5GB  62.5GB  30.0GB  btrfs        primary
 4      62.5GB  77.5GB  15.0GB  ext3         primary
 5      77.5GB  92.5GB  15.0GB  ext3         primary
 6      92.5GB  108GB   15.0GB  ext3         primary
 7      108GB   256GB   149GB                primary  lvm

sda1 is a minimal openSUSE 13.1 install that is updated to openSUSE Factory. 
sda1 is used for booting, troubleshooting and installs.  grub2 on sda1 is used
to boot an OS on sda2 - sda6.  sda2 - sda6 are the OS installs that I use on a
daily basis:

sda2: opensuse 13.1 (daily work)
sda3: SLES12 (beta/RC testing)
sda4: SLES11 SP3 (customer demos)
sda5: SLERT11 SP3 (testing)
sda6: formatted ext3, no OS

I run "grub2-mkconfig -o /boot/grub2/grub.cfg" when booted on sda1.  SLES12 on
sda3 is detected but none of the boot entries are written to the grub.cfg on
sda1.

I created the attached patch for /usr/lib/linux-boot-probes/mounted/40grub2 as
a workaround for my configuration.