The Samsung Magician says it's unsuported, so I don't know what's up with that, I have an image here: View: https://imgur.com/gd7kHLbThat looks very wrong.
What motherboard do you have?
Have you ran a health check on the drive itself? the PM961 is an OEM variant though, so not sure if Samsung Magician can be used with it to check...
Did you install an OS on there? If so, clone? Or reinstall?
Ehm is that the setting in BIOS? I remember something about ACHI from installing my SSD, should I change it to ACHI for the m.2 ssd if it isn't already?Is the SATA Mode Selection @AHCI ?
What does the description in " NVMe Configuration" say about the M.2 NVME PCIe SSD if installed (pg.62) ?