Summarize the question. (e.g., "How to run reconstruction system with RealSense D435i? ")

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

Hello,
I have been trying to visualize 3D models in Open3D-Python by using the following code:
```
import open3d as o3d
model = o3d.io.read_triangle_mesh("nk1.glb")
model.compute_vertex_normals()
o3d.visualization.draw_geometries([model])
```
The issue is that even though the 3D model has texture, it's not being displayed in the visualization window. The model appears with a default grayish color.

Even though the model appears with color on other platforms
The same is not true in Open3D

Using ```model = o3d.io.read_triangle_mesh("cc.obj", True)``` isn't working for .obj models with .png texture files either