Situation: Insane / Insane Game, the AI walked his sovereign into a narrow path, heading southwards towards some lairs.  I saw that, and my hero was also close to these lairs, so I decided to use some units to block him, forcing him to either declare war or turn around.

Instead.... he just stands there.  For the past 4-5 turns.  And he's had friends join him in standing there.

(Screenshot of situation below)

http://cloud-2.steampowered.com/ugc/1118296799450278460/553499D1B24EC71FC5929EA3B98A7D82E25F807F/

I think the AI needs a bit of a logic change, to either choose to declare war on me for blocking his path with random units, or to decide to go after something else other than the lair he's focused on, and thus just sitting there as a result..

Realistlcally speaking, since AI armies only get 2 movement/turn, you could do this exact same thing, anywhere on the map, with 5 individual units, by forming a 'U' shape around the enemy.