http://images.akamai.steamusercontent.com/ugc/545299607733903749/81FB55E7796C730F9A1FFE1795F893416664FC4B/

See the picture, the bridge has a rather large gap to the terrain, the player can make the jump but own troops won't.

Trying to lead them around the bridge doesn't work either, since when the player is on the other side, they'll actually go backwards, leave the river bed and try to cross the bridge instead, even if they're standing in the river almost on the other side.

At least Kofu and another city have this issue.