PySimpleGUI and matplotlib demo program not working on my Pi4

This question relates to a previous query about a program that used to run on a Pi3 but not an upgraded Pi4.

The demo program:

https://github.com/PySimpleGUI/PySimpleGUI/blob/master/DemoPrograms/Demo_Matplotlib_Ping_Graph_Large.py

is the program I based my own on. This demo does not work correctly in Spyder, nor from the command line. The demo hangs (actually, times out) when trying to ping google.com. (Yes, I can ping google from command line.) My only guess is that I have some sort of permissions problem because I installed various libraries with the option, --break-system-packages. Any idea how I can fix this?