Yup, oddly enough, from the beginning, the 2TB HDD showed up in Disk Management as "healthy" and "working properly," with the proper partition, as well as the 256GB SSD. Thing is, it was named Disk 0, with no letter designation, and I think that's the only reason it wasn't showing up in File Explorer under This PC. As soon as it was renamed (D:,) [coma added only so board doesn't show a smilie], it showed up. I think it needs to be designated with a letter and colon, (anything but A or B), and the letter and colon HAVE to be in parenthesize.