"Jack
The achievement wasn't applied with spying due to a typo in code two weeks ago, that's why I was asking, to confirm you were a victim of it. It has been fixed for a while but couldn't be retrospectively applied to managers who missed out. I'll add the achievement to your account manually. :)
I'm currently seeing this now Jack. I have 100% internals on my car, but I'm not getting the achievement. I got to 100% almost purely through spying.
Just FYI in case this is still an active bug and not by design.