I'm building a system on a Classified K with two Samsung 950 PRO M.2 512GB drives.  At first, I couldn't get the BIOS to see either of them.  After upgrading it and tweaking a few settings, one of them (I think the one in the largest slot) showed up, but not the other one.  I've installed Windows 10 on that drive and updated all the drivers from the EVGA downloads page.  I still don't see the second M.2 drive.  I've even installed the Samsung NVMe driver but it didn't help.
 
Is there some other BIOS setting I need to enable/disable to get the second M.2 drive to show up?  The only other SATA devices I have connected are a 1TB SSD on SATA port 0 and a Blu Ray drive on port 1.  As far as cards, I have two 1070's in the first two slots and a Sound Blaster Z in the x1 slot.
 
Any ideas/suggestions?