Unable to chain-load Debian

[William]

Hello.

I currently have two GNU/Linux installs on this PC on two different
SSDs with their own GRUB, Guix and Debian. 
Both SSDs have an MBR partition table, no GPT/EFI.

I've been trying to add a menu entry to chain-load Debian from the Guix
GRUB menu but it doesn't seem to work as intended, upon loading the
declaration file, I check the grub configuration file at
"/boot/grub/grub.cfg" and I see the menu entry for Debian, but it
has no partition UUID defined, I don't think this entry can ever work
without UUID.

The menu-entry declaration is written as follows:

```
(menu-entries
            (list
            (menu-entry
            (label "Debian GNU/Linux")
            (device (uuid "2892086a-fc4f-4e43-8b69-46a84d80e9a4" 'ext4))
            (chain-loader "+1"))))
```

As you can see, the device UUID and filesystem type is defined, but this
string has no effect on the grub.cfg, and it looks like there's a lot of
important information missing:

```
menuentry "Debian GNU/Linux" {
  
  chainloader +1
}
```


Am I missing something?