Advanced Chart Options - How to add multiple options?

I am trying to add two simple customizations to a chart: Add Y-Axis label, and enable X-Axis gridlines. Using the Chart Options (advance) input field in the app, I am able to apply ONE of these using the syntax discerned from the documentation they work individually, but I can’t seem to figure out the proper way to add BOTH together. For example if I use the input:

{“scales”: {“primary”: {“title”: {“display”: “true”, “text”: “% Load”}}}}

The y-axis label is added to the chart. Similarly, if I user the input:

{“scales”: {“xAxes”: {“grid”: {“display”: “true”, “drawOnChartArea”: “true”}}}}

The grid lines are correctly displayed. But if I add BOTH to the input field, the chart will not render. I have tried different delimiters between the inputs (CR, space, comma, etc.) but these do not seem to work. Do the parameters need to be somehow “bundled” together into one line?

I presume I am missing something very simple, and any help is appreciated!