grub2 видит, но не пишет в конфиг другие ОС

sda                ..  disk 
├─sda1             ..  part /boot
└─sda5             ..  part 
  ├─dft-xubuntu16  ..  lvm  /
  ├─dft-xubuntu    ..  lvm  /mnt/xubuntu // !! can't boot here
  ├─dft-swap       ..  lvm  [SWAP]
  ├─dft-storage    ..  lvm  /mnt/storage
  └─dft-mint       ..  lvm  /mnt/mint    // !! can't boot here

> grub-install --version
grub-install (GRUB) 2.02~beta2-36ubuntu3

> sudo os-prober 
/dev/mapper/dft-mint:Linux Mint 17.3 Rosa (17.3):LinuxMint:linux
/dev/mapper/dft-xubuntu:Ubuntu 16.04 LTS (16.04):Ubuntu:linux

> sudo update-grub
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.4.0-22-generic
Found initrd image: /boot/initrd.img-4.4.0-22-generic
Found memtest86+ image: /memtest86+.elf
Found memtest86+ image: /memtest86+.bin
Found Linux Mint 17.3 Rosa (17.3) on /dev/mapper/dft-mint // founded !
Found Ubuntu 16.04 LTS (16.04) on /dev/mapper/dft-xubuntu // founded !
done

### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
	...
}
if [ "${recordfail}" != 1 ]; then
  ...
fi
export linux_gfx_mode
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-28f49a9b-2c1f-43f6-94cf-b83b2d9482a5' {
	...
}
submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-28f49a9b-2c1f-43f6-94cf-b83b2d9482a5' {
	...
}
### END /etc/grub.d/10_linux ###