This has troubled me from the OFP days and is one of the reasons why I prefer missions where you never get to lead. When I'm commanding a squad, my AI teammates are as useless as the pope's balls. They rarely engage enemies themselves, but the moment I leave my earthly dwelling, they put their act together and shoot commendably until there is no enemy left. Is there a trick to this or what? If I give "engage at will" at the start of the mission it makes no difference.