Instale o grub manualmente
# grub-install --target=x86_64-efi --efi-directory=esp --bootloader-id=GRUB
Wandering Wolverine
# grub-install --target=x86_64-efi --efi-directory=esp --bootloader-id=GRUB
# grub-mkconfig -o /boot/grub/grub.cfg
sudo apt install grub-efi grub2-common grub-customizer