I updated my post above.
Seeing the ‘IPython is not defined’ from your code reminded me of how I suggested ipympl for someone who didn’t include code, & another one without shared code cited in my reply, where they say that message and it helped.
I cannot believe I somehow had not connected yet that use of ipympl will also enable FuncAnimation() from matplotlib.animation to work in JupyterLab and by extension, Jupyter Notebook 7+.