Can't scroll to bottom in jupyter notebook with reveal

Question

I am trying to present a jupyter noteboow following this description: https://medium.com/learning-machine-learning/present-your-data-science-projects-with-jupyter-slides-75f20735eb0f

I have large plots through which I want to scroll, but the scroll bar does not appear if I run

jupyter nbconvert test.ipynb --to slides --post serve --SlidesExporter.reveal_scroll=True

An MWE would be this cell tagged as a slide:

import matplotlib.pylab as plt 
fig = plt.subplots(figsize=(10, 20))

I can zoom out in the browser to view the entire slide, but the slide will remain in the bottom half of the screen.

How can I get scrolling to work nicely?

I am running nbconvert 5.4.0.

Thanks for your help!

Torietorii