I'll have to check this out. You should remain clocked as long as you don't:

* Pick up an item
* Interact with something (like an elevator switch)
* Enter an area that triggers a loading screen
* Pick a lock
* Open a side door
* Land an attack on an enemy
* Perform a takedown
* Shoot

... but ordinary movement should be fine.

Of course, you need to make sure that it's activated properly. To activate it, stand (don't crouch) perfectly still in a spot with no security devices or personnel around, and no alarms going off, for five to six seconds.

Yes, that's how it's supposed to work and how I'm used to it working. Since the other two outfits are useless, I've used this one in multiple playthroughs.

It's just bugged right now. Movement breaks the invisibility.