The interactive maps in Visualization - Maps finally displays correctly and can be played with! The previous display failure was due to a build warning when Github was (re)building the website following push:

Liquid Warning: Liquid syntax error (line 470): Unexpected character & in "" in Viz-Maps.html

The warning shows that there is this unexpected character “&” in a line in a certain .html file. This file happens to be the one that displays the interactive maps.

To fix this:

1. Go to the .html file where the warning occurs (in this case, it's Viz-Map.html which has the interactive maps) 

2. Search for the code line that gave the warning 

3. Add a space between the open and closing pairs curly brackets so they become `{ {` and `} }` 

4. Save the file and update the changes (git add, git commit, git push)

Moral of the story: If a page-build failure occurs after git push, a lot of troubleshooting time could be saved by first checking the build log (under the “Action” tab of the repo) before moving on to exploring other possible causes/solutions.