Style.theme.distribution.count not working

[simon-leech]

I can't seem to get a style.theme.distribution.count to work properly. On initial load it loads up the values in square brackets but it doesn't update when you zoom in or out. My configuration is as per the Config Docs

{
  "params": {
    "viewport": true
  },
  "style": {
    "theme": {
      "title": "Category",
      "type": "categorized",
      "field": "category",
      "distribution": "count",
      "cat": {
        "Fashion": {
          "icon": [
            {
              "type": "target",
              "fillColor": "#6F0080"
            }
          ]
        },
        "Food & Beverage": {
          "label": "Food & Beverage",
          "icon": [
            {
              "type": "target",
              "fillColor": "#ffbf45"
            }
          ]
        },
        "Grocery": {
          "icon": [
            {
              "type": "target",
              "fillColor": "#009EBA"
            }
          ]
        },
        "Health & Beauty": {
          "label": "Health & Beauty",
          "icon": [
            {
              "type": "target",
              "fillColor": "#C6003F"
            }
          ]
        },
        "Home & Garden": {
          "label": "Home & Garden",
          "icon": [
            {
              "type": "target",
              "fillColor": "#83b923"
            }
          ]
        },
        "Non-Retail": {
          "icon": [
            {
              "type": "target",
              "fillColor": "#F97248"
            }
          ]
        },
        "Other Retail": {
          "label": "Other Retail",
          "icon": [
            {
              "type": "target",
              "fillColor": "#1A237E"
            }
          ]
        }
      }
    },
    "default": {
      "icon": {
        "type": "dot"
      }
    }
  }
}