Applying Plot Layouts to NodeJS instances

I’m using the NodeJS tool (Copied from GitHub - plotly/plotly-nodejs: node.js wrapper for Plotly's Chart Studio Streaming and REST APIs) to as a rapid-prototyping bed for new plotting tools before I deploy them to our server. However, it doesn’t seem to respect my layout.

Using this set of options:

const imgOpts = {
layout: {
xaxis: { title: ‘GC%’ },
yaxis: { title: ‘Percentage of Sequences’ }
world_readable: false,
format: ‘png’,
width: 1000,
height: 500

and this call to NodeJS:

plotlyNodeJs.getImage({data: traces}, imgOpts, function (error: any, imageStream: any) {
if (error) return console.log (error);

var fileStream = fs.createWriteStream(output);

I’m getting a PNG plot of the expected dimensions and type, but no axis labels:

What am I missing?