Talk:Ghost/@comment-66.242.70.217-20150709160943/@comment-16241899-20150710151208

If an alarm sounds, you have been detected anyway, since someone has to activate it, and they don't activate it unless they've spotted you.

Did you do a solid playthrough and Ghost checked in the stats after every mission?

If yes, then it is probably really a bug. It is a known problem that some achievments occasionally don't unlock even if you did everything right.