Boot failure on NVME drive fresh install of Ubuntu 16.04

I have and Asus Z97-Deluxe/USB 3.1 motherboard, and just installed a Samsung 950 Pro on an Asus Hyper M.2 X4 Mini expansion card, which I inserted it into the 2nd PCIEX16 slot (PCIE 3.0) on the motherboard. I unplugged all of my HDDs and booted to the Ubuntu installer on a USB thumb drive. The installer saw the disk, allowed me to set partitions (which included a 200MB efi partition, which I pointed the boot loader to), and began to install. During the first attempt, everything went smoothly, but when I went to reboot, it failed to boot at all. It didn't even to a GRUB screen, let alone the Ubuntu splash screen. I then reattached my HDDs, booted to Windows 10, used diskpart to clean this NVME drive, and then tried again. This time the Ubuntu installer gave the error:

Unable to install GRUB in /dev/nvme

Executing 'grub-install/dev/nvme' failed

This is a fatal error

Also, I tried setting CSM (Compatibility Support Module) to [Disabled] in the BIOS before the install. Although it installed cleanly this time, upon reboot I get the follow error from the BIOS:

Notice

The current BIOS setting do not fully support the boot device.

Go to Advanced > Boot > CSM Parameters, and adjust the CSM (Compatibility Support Module) setting to enable the boot device.

If I re-enable CSM, the system fails to boot (without loading GRUB).

Any ideas? I didn't have these problems with the same NVME drive when coected directly to the motherboard's M.2 slot. In fact, I used to see "ubuntu" listed in the boot options in the BIOS under that setup.