First call to update method has empty dataView

Hi,

For some reason, the very first call to my visual's update does not populate the options argument with any dataViews (and thus no data), but on subsequent calls it does. The first call also seems to have a different "type"; 62 instead of 2, although what this means I have no idea (Even the API docs don't mention a "type" property!).

In my update method I simply do a console.log(options), and this is what's produced after several updates (the top one is irrelevant):

As you can see, there's something different about the first call.

Here's my capabilities.json, I think it's structured correctly:

{
  "dataRoles": [
    {
      "displayName": "Solution areas",
      "name": "solutionAreas",
      "kind": "Grouping"
    },
    {
      "displayName": "Pillars",
      "name": "pillars",
      "kind": "Grouping"
    },
    {
      "displayName": "Statuses",
      "name": "statuses",
      "kind": "Grouping"
    },
    {
      "displayName": "Names",
      "name": "names",
      "kind": "Grouping"
    }
  ],
  "dataViewMappings": [
    {
      "table": {
        "rows": {
          "select": [
            {
              "for": {
                "in": "solutionAreas"
              }
            },
            {
              "for": {
                "in": "pillars"
              }
            },
            {
              "for": {
                "in": "statuses"
              }
            },
            {
              "for": {
                "in": "names"
              }
            }
          ]
        }
      }
    }
  ]
}

Any ideas what could be causing this? This is a brand new project so I haven't tinkered with anything really, just capabilities.json and the update method.

Thanks.