I would like to build a query that has multiple groupByFieldsForStatistics. However, when I put a multi-item list in, I see no evidence of the second (or beyond) field in the query results. The below codepen is an example - I'm trying to group the data by magType and place, but see no evidence of place in the response (the first item of which is logged to the console and shown at the top of the page for convenience)
Unfortunately, Query.groupByFieldsForStatistics does not support multiple fields on client-side layers and layerviews. We have an issue for this. I will let you know when we fix it.