python-created render window is blank

I am trying to use self-compiled paraview-python (from an iPython shell) on Mac. I was able to build Paraview and link to my preferred python (v-3.8). Using the python shell from the Paraview gui works fine:

Sphere()
Show()

shows the expected sphere in the default render window. However, these commands in my iPython shell:

from paraview.simple import *
Sphere()
Show()
Render()

opens a blank render window. The background is a light gray, not the mid-level gray that is the default background color. This has worked for me in the past on Mac, but it has been long enough that I cannot recall what Paraview and Python versions.