Sample code gives different visualization result

So if I run the code below like a simple script: `python3 map_viewer.py` it produces a nice map.

But if the same code I run from my app, where I trigger `MapViewer().show()` on button click I get this:
Points here are aligned along grid.

```python
import numpy as np
import open3d as o3d

class MapViewer:
def __init__(self):
super().__init__()

self.pcd = None
self.vis = o3d.visualization.Visualizer()

def load_point_cloud(self, filepath="/home/stsdc/test.pcd"):
self.pcd = o3d.io.read_point_cloud(filepath)

def show(self):
self.load_point_cloud()

if self.pcd:
self.vis.create_window()
render_option = self.vis.get_render_option()
render_option.point_size = 0.7
render_option.background_color = (0, 0, 0)
self.vis.add_geometry(self.pcd)
self.vis.run()
self.vis.destroy_window()
else:
self.vis.destroy_window()

MapViewer().show()
```

Please help, I feel dumb :roll_eyes: .