labelOpacity expression bug

labelopacity-expression-bug.json

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "description": "A dual axis chart, created by setting y's scale resolution to `\"independent\"`",
  "width": 400, "height": 300,
  "data": {
    "url": "data/weather.csv"
  },
  "params": [{"name": "toggleHighlight", "bind": {"input": "checkbox"}}],
  "transform": [{"filter": "datum.location == \"Seattle\""}],
  "encoding": {
    "x": {
      "timeUnit": "month",
      "field": "date",
      "axis": {"format": "%b", "title": null}
    }
  },
  "layer": [
    {
      "mark": {"opacity": 0.3, "type": "line", "color": "#85C5A6"},
      "encoding": {
        "y": {
          "aggregate": "average",
          "field": "temp_max",
          "scale": {"domain": [0, 30]},
          "title": "Avg. Temperature (°C)",
          "axis": {
            "titleColor": "#85C5A6",
            "titleOpacity": { "expr": "toggleHighlight ? 1 : 0.2" },
            "labelOpacity": { "expr": "toggleHighlight ? 1 : 0.2" }
            }
        },
        "opacity": {
              "condition": { "param": "toggleHighlight", "value": 1 },
              "value": 0.2
            }
      }
    },
    {
      "mark": {"stroke": "#85A9C5", "type": "line", "interpolate": "monotone"},
      "encoding": {
        "y": {
          "aggregate": "average",
          "field": "precipitation",
          "title": "Precipitation (inches)",
          "axis": {
            "titleColor":"#85A9C5",
            "titleOpacity": { "expr": "toggleHighlight ? 0.2 : 1" },
            "labelOpacity": { "expr": "toggleHighlight ? 0.2 : 1" }}
        },
        "opacity": {
              "condition": { "param": "toggleHighlight", "value": 0.2 },
              "value": 1
            }
      }
    }
  ],
  "resolve": {"scale": {"y": "independent"}}
}