Is the USB 3.0 an addon card or did it come with the PC? There seems to be a lot of problems with USB 3.0. Did you make sure the drivers are updated? Also check the drivers for the USB controller. Did you look on the Seagate forum?
The Hard drive is getting power, the light is on, but it just does not show up at all. Ive been checking everywhere for this problem even the seagate forum. I have checked drivers and they say they are up to date.
Something else I remembered seeing. Some computers the USB 3.0 port slows to USB 2.0 speed if you have a device plugged into the USB 2.0 port. Try removing things from your USB 2.0 ports if you have anything connected there.
WD has problems with the USB port on the circuit boards too. It's probably a poor solder job with the lead free solder they have to use now. I wouldn't trust the drive if the port breaks off you're screwed. Or the drive might get corrupted.