You've got this drive hooked up inside a desktop PC, using a standard SATA data cable, and a SATA power connector from the power supply, correct?
When you connect it using USB, can you describe how you do this? (Is it it the external drive casing? Do you have an adapter you are using? etc.)
You could try the diskpart procedure while the drive is connected by USB.
You can also try using the command list disk instead of list volume, although that should not make any difference.