VivoBook S14 S431FLC - Can't enable CSM option | Can't boot Grub EFI

[Gps3dx]

Hi all,
Recently I purchased VivoBook S14 S431FL.

I have two MAIN issues, and another minor:
1. Even though I managed to disable Secure Boot in the UEFI - I don't get the 'CSM option' in the UI so I can't emulate legacy boot ( which I want so that I can boot various portable OSs ).
To disable Secure Boot, I had to set admin password -> then delete each of the Secure Boot keys ( not sure if a reboot was needed after saving changes).
BUT even after secure boot was disabled -> NO "CSM OPTION" appears in the UEFI UI menus - even though it is most probably exist & hidden, as the secure boot info reminds that for secure boot to work, csm option needs to be disabled !

2. Since NO 'CSM option' available in the UI - I have to "UEFI boot" any OS.... i.e using EFI files.... it is annoying and complicated but still possible.... so I though so - BUT NO:
When I try to boot grubx64.efi of various grub versions ( 2.20, 2.40 ) from FAT32 formatted USB ( like SuperGRUB disk ) - grub loads BLACK SCREEN WITH A STUCK/FREEZE WHITE CURSOR - and the laptop enters NO GRUB MENU/SHELL at all.
This happens as well with different grubx64.efi version and releases from different sources: ubuntu, supergrub disk etc...
I tried to boot from different USB socket with different USB sticks ( usb 2.0/3.0 sticks )-> grub gets stuck/freeze.
I tried multiple GRUB EFI version (2.20, 2.40 and older ) -> grub gets stuck/freeze.
I tried to boot with VT-d and CPU virtualization option disabled in the UEFI -> grub gets stuck/freeze.

According to THIS SOURCE, such behavior is explained due to CPU microcode fault -> thus it is UEFI/BIOS FAULT -> ASUS FAULT !!!!!

3. My laptop BIOS/firmware version is X431FLC.203 ( i.e 203 ), and please note:
A. the firmware model name for S431FL serie is 'X431FL' - and AFAIK there are two sub-model: "C" and "AS".
B. The "C" postfix meaning my laptop is sub-model C, so firmware that was designed for 'AS' model is NOT compatible with my laptop.
Thus when firmware 204 & 300 do exist for 'AS' sub-model, they are NOT AVAILABLE FOR MY MODEL AS IT IS DIFFERENT SUB-MODEL !
The ONLY PLACE between the many Official asus websites that I found the CORRECT FIRMWARE download list for my sub-model "C" is HERE, and currently the latest firmware version available is 203 - which is the one my laptop got.

Why don't asus include the "C" submodel firmware in the official S431FL download page - is a mystery in of it self.
P.S - AFAI understand, my "S431FL" laptop which got firmware "X431FLC" ver 203 - actually got out-of-the-box firmware that belongs to "UX431FL" laptop !!!
W-T-F ASUS ?!


That being said:
DEAR ASUS: PLEASE UPDATE VIVOBOOK S14 S431FLC (aka X431FLC) BIOS !!!

1. Please UN-HIDE ( i.e SHOW ) "CSM OPTION" when the user disables Secure-Boot.
2. Please FIX ( update or downgrade ) CPU microcode so that UEFI boot of GRUB EFI will be possible.
3. Please UPDATE you "drive & utility" section for the S431FL model, so that it will include the firmware for sub-model "C" as well, and in ALL OF YOUR SUPPORT WEBSITES AROUND THE WORLD ( e.g. us, uk, il, tw etc ).

Yes, I know this is a users forum - not direct line of communication with Asus... BUT I ALSO KNOW that some limited Asus employes are indeed found here, as i'm a veteran user in the G-serie sub-forum.
@MASON@ASUS @CL-ALBERT, @MasterC@ASUS, @xeromist, @Bahz - can you please forward this request to appropriate personal in-side Asus ?
Much Oblidged.
GPS

[Gps3dx]

Regurding CSM option - Just saw this FAQ article in Asus support site.
WHAT A BULL-S**T !!!
The fact that only windows 10 support latest CPUs ( and not win7/8/8.1 ) DOES NOT MEAN YOU HAVE TO HIDE CSM OPTION IN THE UEFI UI !!!!
IT EXIST IN THE UEFI FIRMWARE SINCE AMI PUT IT THERE - YOU (ASUS) CHOSE TO HIDE IT NONETHELESS - SO YOU CAN CHOOSE TO UNHIDE IT !
Windows 10 OFFICIALLY supports legacy boot on MBR formatted drives - so again - BULL-S**T !!!
IT IS YOUR OWN (ASUS) DECISION TO HIDE/BLOCK ACCESS TO CSM OPTION FROM UEFI MENUS - STOP BULL-S**T YOUR CLIENTS !!!!

[Gps3dx]

Asus released BIOS Version 301 dated 2020/05/14 with changelog of "Optimize system performance".
so in short:

• CSM option was NOT returned !!!
• NO fix for the inability to boot grub !!!
• the "update" is WINDOWS INSTALLER ONLY - you HAVE to install it to actually get the BIOS binary - WTF ?!
  why can't you separate the BIOS and its installer like you did so far in any other product, desktop/laptop/motherboard you sell !?

SHAME SHAME SHAME