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> I think you'll need to inspect the boot script (grub.cfg) to trace the
> steps it takes to build up your partitions abstraction stack. Just off
> hand I would guess it lacks an f2fs module in the efi collection; or
> perhaps worse, that the uefi boot is set up as a chain loader that
> will want modules in the /boot/grub directory of the main partition.

Grub is not getting as far as loading it's own menu.
That may well be the case.

> UEFI boot requires the bootloader to reside in the EFI/FAT partition,
> and the grub bootloader is modular with the primary part grub64.efi
> and a bucket of support modules to handle things like lvm2 setup and
> f2fs formatting as well as display variants etc. Those modules reside
> somewhere and obviously they must be accessible for bootloading
> without disk abstractions.

OK it seems that I may be mistaken in how grub-efi-amd64 works.
I had in my head that it was a totally different beast to grub-pc but what you say suggests not.

> I believe the grub setup designers have thought about that and can
> handle many cases but presumably they have missed something for your
> setup case. So that would be the first thing to look into and verify.
>

> Ralph.

I have some heavy reading to do.

After burning the midnight oil last night I am too tired to do any more this evening.

Thank you for the guidance.