I tried several times, without any change to the boot menu. The SDD device (perhaps a specific part) and also a "windows boot manager" are items in a menu when rebooting with Advanced Startup from Windows.

The steps I used were:

- Ran grub-mkconfig -o /boot/grub/grub.cfg - changed the permissions of that file to +w - re-ran grub-mkconfig

Why are you doing this? You generally shouldn't need to set the +w on /boot/grub/grub.cfg. It should be set correctly for from the beginning. Remember you should be root or using sudo when running grub-mkconfig to write to /boot/grub/grub.cfg $ ls -l /boot/grub/grub.cfg -rw------- 1 root root 6209 Apr 22 18:29 /boot/grub/grub.cfg

Each time I ran this, it saw the Arch partition. And each time I booted, this was not found in the grub menu at boot time. It was shown as

1. You should check the contents /boot/grub/grub.cfg actually contains the menu entries for Arch Linux 2. If you do see Arch Linux the menu entries in /boot/grub/grub.cfg but then don't see them at boot then that mostly likely means /boot/grub does not contain the grub files you are actually using at boot time (i.e. your /boot is mounting the wrong thing!). Either that or the menu you're looking at when booting isn't even GRUB!