Windows 10 Install and Boot: Predator G9-791-735A from PCIe NMVe SSD

Been trying off and on to figure out this problem.
Bought a new Western Digital SSD - 1TB - PCIe NVMe.
Installed the drive into Slot 0 and moved the LiteOn 128gb SSD to the Slot 1 ( Only Slot 0 will accept a NVMe )
BIOS and Windows recognized it with no issues. The laptop booted up quickly as it always does.
Tried to clone my pre installed SATA SSD 128gb to it. That worked.
Thought everything was gravy, then:

ISSUE:
Windows or the laptop will not boot from that drive. No matter what I do.

Gave up trying to clone and tried fresh install of Windows 10.

ISSUE:
Windows will not let me install to that drive. No matter what I do.
Tried adding the drive to the UEFI db.
Tried clearing the UEFI.

What gives?

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Gawain

just a quick clarification - when you're trying to install a fresh 10 image to the new ssd, is the old ssd still plugged in (with the original copy of 10 on it)? if so, the original ssd has efi partition on it and that means you cannot install completely to another ssd whilst the 10 installation process recognises the original partition and therefore won't write a new one to the other ssd. Personally i'd remove the original at the mo., try loading 10 onto the new one, and if that works, then deal with the old ssd.