The wrong case video
I hope zombie can void the landmine by set the read area with NavArea_Obstacle.But it don’t work somtime.
Could you update this post with some more information. It is very hard to help you unless you provide any images or more information.
As the video show, I have set a navmesh modifier box overlap the landmine, and zombie will always chase the player. At first, the zoombie can avoid the landmine bypass the red box area, but zoombie may enter the area after player walk along the edge of red area some times.
I am not sure of the proper solution due to my limited knowledge on AI. You could however create a collision box around the mine that is only a working collision for the zombie. In the case of that, you will not have to worry about it ever being triggered or walked through.