I can't unlock this achievement despite meeting (I suppose) conditions. Unless there are some "secret" requirements - does difficulty level or AE content matter? Do I need some extra augments, like "stealth weapons"? Does it have to be done during first cloak?

I had no problems with other achievements I've unlocked so far. The game imported save files from Steam version, but I didn't have unlock Stealth Cruiser while playing on Steam.


EDIT - solved

OK, I've upgraded Cloaking to 3rd tier (just like FTL Wiki recommends), found scout drone without the shield and kaboom, unlocked.

This was one I struggled with as well. There was always something that impeded progress - I'd forget to enable autofire, the scout ship would have more shields than necessary, etc. Finally got lucky and was able to wipe out a scout ship before the cloak timer ran out.

I think this is a common one for general confusion though, but I don't know how they could convey it more clearly to the player to make it easier to understand either.