I have this vague recollection from one or two earlier playthroughs that during one of the mission maps, some cloaked dudes show up, theres some Ashley/Mr. Riggs dialogue, and you suddenly can use Cloak. Separate from scanning enough of them to unlock the tech/blueprint. Tried Googling and couldn't find anything about that, though I feel like I went on this journey once before and got reminded of the mission thing from some website.