Bug in rendering Volumetric density data?

I don't know if this is a hardware problem but when I try to execute this code from [this StakOverflow answer](https://stackoverflow.com/questions/25286811/how-to-plot-a-3d-density-map-in-python-with-matplotlib/25354417#25354417):

```
import numpy as np
from scipy import stats
from mayavi import mlab

mu, sigma = 0, 0.1
x = 10*np.random.normal(mu, sigma, 5000)
y = 10*np.random.normal(mu, sigma, 5000)
z = 10*np.random.normal(mu, sigma, 5000)

xyz = np.vstack([x,y,z])
kde = stats.gaussian_kde(xyz)

# Evaluate kde on a grid
xmin, ymin, zmin = x.min(), y.min(), z.min()
xmax, ymax, zmax = x.max(), y.max(), z.max()
xi, yi, zi = np.mgrid[xmin:xmax:30j, ymin:ymax:30j, zmin:zmax:30j]
coords = np.vstack([item.ravel() for item in [xi, yi, zi]])
density = kde(coords).reshape(xi.shape)

# Plot scatter with mayavi
figure = mlab.figure('DensityPlot')

grid = mlab.pipeline.scalar_field(xi, yi, zi, density)
min = density.min()
max=density.max()
mlab.pipeline.volume(grid, vmin=min, vmax=min + .5*(max-min))

mlab.axes()
mlab.show()
```
I don't get the render in the window at all. It is just blanck (but the axes and all the other things are present). But when I save the figure instead of showing it, it indeed [looks normal](https://i.stack.imgur.com/uDiNi.png).

I need to see it in the preview. What is the problem here?
I'm using a Fedora 29 system, with Python 3.6.6 and Mayavi 4.7.1. My graphic card is a AMD RV710.