Does this only happen when you remove the hard drive after shutting down, to the point that it’s an isolated incodent? I can’t give a vivid answer but what I’d suggest until one can is to “safely remove” any WD you want to move, because it may not be displaying lights or sending information, but may be still in a way connected to the computer, and running.
I have noticed that when my computer is off, and the power to the computer is resurged (unplug the power cable, replug the power cable) the my book disk will spin.
For now if you know you are going to be moving the my book around, safely remove it before shutting off the computer.
