Cannot boot from new NVMe SSD drive to which old SSD has been migrated.

Hi. I have windows 10 64 bit, an Asus Z97-AR motherboard and a Crucial Sata SSD with Windows and booting.
I also have a new Crucial 1000GB PCLe NVMe drive in the M>2 port.
I had a problem getting the PC to recognise the NMVe when first installed, despite the motherboard being UEFI BIOS.
The reason, I came to believe, was that I needed to convert from MBR to GPT.
Having done so, I found that the NVMe was now recognised.
I then tried to clone the Sata SSD to the NVMe using Macrium Reflect.
The process seemed straightforward and was marked as having succeeded. But the desktop fails to boot from the NVMe, or to boot at all if I remove the SSD.
The same thing, too, if I make an image rather than a clone.
The BIOS Boot Priority panel has three entries: Generic-SD/mmc; P4:Asus BW-16D1HT; and Windows boot manager, which has the name of the SSD in brackets. This latter disappears when I disable the SSD..
There is no sign of the NVMe. In the BIOS;also,the M.2 is what I have chosen when the option was between it and the PCL1 port or ports..
I'd be grateful for any help, especially if someone can advise me as to the possibility of wiping the NVMe, which presumably now has an SSD clone or image on it, and clean installing Windows 10, not from the SSD but from Microsoft. It still is free to download and install, by the way..
I've attached a screenshot of the disk management table
Cheers, Laurence