No output in mayavi window

I am running OsX Catalina and installed mayavi via anaconda with python 3.7. Installed package verisons are:

```
mayavi 4.7.1 py37ha91d4f2_2 conda-forge
vtk 8.2.0 py37hb651df3_207 conda-forge
```

Trying to run a simple example opens up the mayavi window but there is no figure displayed (window is all black). I tried taking a screen capture but that shows an all-white window. The buttons respond by clicking about half an inch below the actual buttons (where they are drawn when clicked)

I tried running the following example code in Ipython. With ipython. Calling show() is required when ipython is called with no command-line arguments, running it with ipython --gui=qt does not require show(). I also ran a simple vtk example directly which worked fine, so I'm assuming that the problem is not with VTK.

Sample code is:

```
import numpy as np
from mayavi.mlab import *

def test_plot3d():
"""Generates a pretty set of lines."""
n_mer, n_long = 6, 11
dphi = np.pi / 1000.0
phi = np.arange(0.0, 2 * np.pi + 0.5 * dphi, dphi)
mu = phi * n_mer
x = np.cos(mu) * (1 + np.cos(n_long * mu / n_mer) * 0.5)
y = np.sin(mu) * (1 + np.cos(n_long * mu / n_mer) * 0.5)
z = np.sin(n_long * mu / n_mer) * 0.5

l = plot3d(x, y, z, np.sin(mu), tube_radius=0.025, colormap='Spectral')
return l

test_plot3d()
show() % Not required with ipython --gui=qt
```