Thanks to @jasongrout, it may not be necessary to make a shorter notebook to show the differences. @jasongrout is much more knowledgeable than me. However, I think he is pointing you towards what I was wondering would come out of looking at a minimal example. JupyterLab 3 has recently greatly improved use of ipywidgets in notebooks, and so my thinking was maybe issues you are still seeing with widgets in the notebook may be because you were using some widgets-related coding approaches that had somewhat changed over the last few years.