Hi Susan - The map doesn't seem to be shared publicly, so I couldn't access it.
Can you try opening your map in the map viewer BETA, which is also built on the 4.x JSAPI to see if you see the same differences? You can find the MVB in the app switcher at the top right near your profile menu in ArcGIS Online.
Thank you so much for your reply! I've followed your advice. However, opening the existing map to Map Viewer Beta did exactly the same thing (distorted the placement of the Map Notes text). I thought I might be able to use the Edit tool as well, but it would not work in the Beta Version (only allowing me to Edit the shapefile features, not the Map Notes, even though selected). Then, I thought to add a new Map Notes layer as one would do in the older version of Add>Add Map Notes -- but, that is not even an option in the Beta version (yet, maybe?)
At any rate, I've made the map public -- if you have any other thoughts, I'd very much appreciate it!
Thank you again,