Come on CA - Gamedesign, programming or QA bug?

[Nestor]

...But does anyone have any tips for how to minimise "the passive AI bug" until then? When does it kick in? I've heard people say it's related to missile inferiority. Should you then just take, say, one missile unit per stack as I used to do with Romans in RTW/RTR/EB? (This might be ok, perhaps, as the French or some other continentals (Danes, HRE), with a token crossbow unit or two)....

Yes, you can attack at the passive enemy army and have a look at the charging/engaging bug when half of your soldiers are picking flowers spread out at the back of the formation

Seriously, I don't know exactly when this one kicks in, but I've seen it much too often for my liking.