Even after Bitlocker had completed encrypting the drive, I restarted the next day, and the drive didn't mount or even show as a Bitlocker drive.
Now it shows the capacity as 768GB (3TB drive). And this is the drive, not a volume (i.e. /disk3), in the Computer Management utility.
I've tried using a GParted live CD, but the GParted executable would close after several error messages. Should I also try DBAN?
Should I just buy a new drive? If Bitlocker said the encryption process completed, and then it doesn't mount or appear as a volume on the next restart, is that a bad sign?