We have found the solution to this 'problem'. Apparently when a players never shows any passive actions the aggressionfactor will always be 0.0 (0/0). This is possible even after playing more than 100 hands with an opponent. When the opponent is passive for the first time (calling in stead of raising) the stat works fine. I think in HM2 the hud showed "inf.". Now you can't see if an player is very passive or very aggressive if he has never done anything passive.