My Book Encryption

I’m setting up a “My Book” (4 TB) for my boss. I noticed that if I plug the “My Book” into my work laptop (Windows 7) and type in the password, the device unlocks and the files appear. What I’m confused about is if I click on "Safely remove Hardware and Eject Media " and I unplug the device from my work laptop, and plug it into my personal Microsoft Surface (Windows 10) I can see the files and I’m not prompted for the password. It looks like the password prompt only pops up if my work laptop is shut down and I move the “My Box” to my Microsoft Surface.

Working in Information Security, I’m concerned with this finding. If someone unplugs the “My Book” from his laptop and takes off with it, he/she could conceivably have full access to all of the files. Doesn’t this defeat the purpose of encryption?

Please respond when you can. We’re curious about what’s going on.

Thanks,

Dave

Exactly which My Book? Model Number from the label helps.