I have had an issue with both fast ring Versions 14942 AND 14946 coming up with a "performing automatic repair" when trying to boot from my Samsung NVME 950 Pro 500GB drive on a PCI card on my ASUS Sabertooth Z97 Mark 2 mobo. Under the UEFI settings screen, the NVME drive does NOT appear as a Boot Manager option. Nothing fixes it or repairs it. This was not a problem on previous fast ring versions.
The first time this happened, I restored from a clone of version 14936. I finally found a way to boot the drive. I TURNED OFF "Secure Boot" option in the BIOS and selected "Other OS". I am going to test this out further but for now that is my fix.