[PROBLEM] ASRock Fatal1ty Z370 Gaming if - Windows10 won't boot from SSD Plextor M8Pe(G)

Motherboard: ASRock Fatal1ty Z370 Professional Gaming i7
SSD: Plextor M8Pe(G) 512GB
Intel Core i7-8700K, 3.70GHz
Windows 10 Pro 64-bit
UEFI up to date 1.40

I have a problem with my SSD Plextor boot in Fatal1ty Z370. In UEFI boot menu can’t see SSD on list, also on advanced UEFI mode can’t see SSD disk. I have only HDD or can have USB windows installer. But also on Windows 10 installer (USB - UEFI) don’t see SSD on storage list. I can run for ex. CMD only.

Important is fact that all worked well before (for 2 days) now don’t. Windows10 was installed, updated, all worked well etc. I tried for ex. (clear CMOS) but nothing. Also when turn off HDD nothing changes.

In UEFI advanced mode:
Compatibility Support Module → Launch Storage OpROM Policy: UEFI, rest on Legacy.
When CSM disabled also don’t works. Secure mode disabled.
Storage Configuration → SATA Mode: AHCI.

But still don’t see SSD it on Boot menu. Maybe something else that I should change (in UEFI)? Drivers? Please help.

@ffallen :
Welcome to the Win-RAID Forum!

I suspect, that you have either disabled the related M.2 port or forgot to disable the “SECURE BOOT” option within the BIOS.
Another tip: Disable the “CSM” and “FAST BOOT” options, unplug all disk drives except the Plextor M.2 SSD and then boot off the USB Flash Drive with the Win10 image on it in UEFI mode.

Good luck!
Dieter (alias Fernando)

Secure boot disabled, also with disabled CSM nothing change. Tried with unpluged HDD and tried plug SSD to another Ultra M.2 socket but also nothing change.
Not fully understand this: “I suspect, that you have either disabled the related M.2 port” - maybe yes and that’s why not detect SSD how can I enable it?

EDIT by Fernando: Unneeded parts of the fully quoted post and blank lines removed (to save space)

You have to enter the BIOS and to look for the related options.
A look into your mainboard manual may help you to find it.