3D model not rendering properly in unity scene view?

I have a fbx 3D model of a building. In scene view, the side view of the rooftop has disappeared somehow, but I'm not sure what is the cause.

In top view, the rendering works fine.

I tried changing the near and far clipping planes of the camera, making the near clipping plane as large as possible and as small as necessary. Meanwhile I made the far clipping plane as small as possible but as large as necessary. That did not work. I also tried it with both URP and BIRP and both did not work...

What could be the possible cause of this issue and how can it be fixed? I can provide images of the wireframe if necessary. Thank you.

This looks like your model has only the interior modelled. Almost all shaders only render one side, the "front side". That's because it's very difficult to properly light a single triangle for both sides as you only have one normal vector per vertex. If you want the model to be rendered properly from the inside and outside, you usually would duplicate the triangles for the outside and make sure they face the correct way.

Another issue could be the usage of a shader that doesn't write to the depth buffer. This is usually the case with transparent shaders. Though the image doesn't really look like this.

So check which shader you are using and if your model actually has two sides modelled.