I noticed that such a gap in the middle of the occluder is created due to the fact that the occluder is triangulated, if you use a Quads, it becomes better, but still does not work correctly.
And this gap is obtained on the edges.

@Geez look at this, it does not work correctly.
Video:

Model:

Yes, the model is normal, but you see that sometimes objects do not occluded, i think its engine bug.
more video: https://youtu.be/k8iPXdpO2Mw

Rendering of a port garage in Chernarus, this is the last frame of loading models.

Hello.
NiiRoZz:

1. I know it, and my model inside map.
2. Works and outside, you can watch this in video. But and inside geometry have same defect.
3. Occluded inside, as you can see in the video, but it depends on the direction of the look
4. I also thought, but small one has exactly the same problems.
5. Yes, I know, I read wiki before doing this, and I followed all the rules.

Sorry for my English.