I was able to resolve this issue in an off way.
For a given chart, there is the code that generates the chart and an accompanying button that triggers the download.
The code that creates the chart specifies its height and width.
The button executes a function that runs a “Plotly.toImage” command. This command also has a height and a width argument to size the image in the png file.
In both instances, the height and the width of the chart have to be the same in order to include the annotations.
That is, one cannot resize the chart once it has been created.
This doesn’t make any sense to me; the image is created as an SVG – a format that does allow for resizing.
So it goes