My understanding about zones of control is that moving within them costs all movement. Is that not the case? Been multiple times now where I thought I had a unit blocked in with my melee (not ranged) units, and the AI just sent its own melee units around it. In one case, I had a city under siege, and they sent a unit out to smash an archer that was two tiles away. By definition, the siege meant the whole city was under zones of control. Another time, a mounted unit two-stepped around a melee unit to hit a slinger behind it, visibly ignoring the zone of control.