In original Xcom there was such a bug: when aliens start a long project (usually - infiltration) even if I destroyed ALL scout and other ships, when the last battleship arrives - the game thinks that alien mission suceeded it the minute when battleship appears in the sky. At that moment you get massage that some country was infiltrated. And nevermind if I destroy thatbattle ship after few seconds of his appearanse (in the sky of course).
How does this thing work in OpenXcom?