1. In mission editor, start a new mission. Place the player as any soldier, and a subordinate AI soldier anywhere on the map.
2. Preview mission.
3. Pause mission. In debug console, execute the line below:

{_x setpos [7320,7327,0]; _x setdir 48;} foreach (units group player);

4. Unpause. Move forward, through either gap in the fence.
5. Observe subordinate AI get stuck on other side.
6. Feel bad for AI.

Example 800m length of continuous fence AI cannot go through, but players can:

This issue may be due to 2D AI grid pathfinding, and that this fence type model features a continuous strip concrete footing. AI see the pieces with gap as being as solid as the pieces without due to the concrete.

In reality, a continuous concrete footing is just wasted concrete. Concrete is only used around the fence posts. The bottom of chain mesh is held in place by thick wire, cable or tube. See examples:
http://urips.com/good-facts-about-cyclone-fence/