To wrap this topic up for anyone who may experience a similar problem/issue in the future: - Drive is not defective.  Installed in a different machine and operating normally. - tried 2 new cables, 1 OEM and 1 eBay knock-off, neither resolved the issue(s). I can only conclude that there is a HW issue either with the port/cable interface specifically or the board in general.  Immensely frustrating, but not likely worth the time/$$ to replace/repair. Thx to JOcean and filbert for the input.
Hello Community: System is the G3 15 (3500) with 256 GB M.2 (2230) SSD (main drive) + empty 2.5" HDD slot. I need more storage.  I've installed a new WD Blue 500 GB 2.5" SSD into the empty HDD slot, but the system can't seem to decide if it wants to see it or not. After install the BIOS correctly identified the new drive.  After boot Windows also correctly identified the drive, it appeared in the device manager and disk management console.  But when attempting to initialize the drive it simply disappeared. After a reboot, it no longer appeared in BIOS or Win10 device manager.  After another reboot it reappeared in BIOS and Win10 device manager, but disappeared again shortly after. After every boot it is a lottery whether or not the system will recognize the drive.  Have double and triple checked the physical install and BIOS settings, no idea why this is happening.  It's almost like it thinks its a removable drive that's being removed.  Cable perhaps? Would appreciate your help.  Thx.  
Unstable SSD install - G3 15 3500