Windows not seeing HDD

my secondary internal HDD (1TB WD Black) just disappeared from Windows with no warning. I was in the middle of watching a movie off it and next thing I know I get an error that the file location doesn't exist. HDD apparently failed. not visible in My Computer, Device Manager or Disk Management. but it IS recognized by the BIOS and my RAID controller. But the real kicker is that it works completely fine when connected via USB dock. I was able to back up all the data and apparently it hasn't failed at all.

I've tried different power connectors, different SATA cables, reformatting the drive, and tinkering in the BIOS or my RAID configuration but no luck. before I get into Windows everything works fine but once Windows is running, its as if the drive isn't even plugged in.

looking for any ideas right now as I am running out. running Windows 8 Pro x64 for what its worth.