It turns out that by adjusting the chart width and the x-axis label font size, you can get the y axis labels to appear as shown in
https://jsfiddle.net/wittski/5rfavu7z/36/.
This also "fixes" the missing gridlines referenced in this bug:
https://github.com/highcharts/node-expo ... issues/587
It's not just that there's not enough space - making the chart any larger than 400 causes the label to disappear.
I'm using this with the export server, and to make that work I used a chart width of 500.