Boxplot missing/broken whiskers when using timeUnit

[semiamaurotic]

When I try to group data by weekday or month (or any timeUnit) and use "extent": "min-max", whiskers are displayed, but when using the default 1.5 IQR, no whiskers are drawn. If I switch to ordinal or nominal types, detached whiskers are drawn in a new column. This seems to be related to issue #4524

{
  "$schema": "https://vega.github.io/schema/vega-lite/v3.2.1.json",
  "hconcat": [
    {
      "data": {"url": "https://vega.github.io/vega-datasets/data/seattle-temps.csv"},
      "mark": {"type": "boxplot",  "extent": "min-max"},
      "encoding": {
        "x": {"type": "temporal", "field": "date", "timeUnit": "month"},
        "y": {"type": "quantitative", "field": "temp"}
      }
    },
    {
      "data": {"url": "https://vega.github.io/vega-datasets/data/seattle-temps.csv"},
      "mark": "boxplot",
      "encoding": {
        "x": {"type": "temporal", "field": "date", "timeUnit": "month"},
        "y": {"type": "quantitative", "field": "temp"}
      }
    },
    {
      "data": {"url": "https://vega.github.io/vega-datasets/data/seattle-temps.csv"},
      "mark": "boxplot",
      "encoding": {
        "x": {"type": "ordinal", "field": "date", "timeUnit": "month"},
        "y": {"type": "quantitative", "field": "temp"}
      }
    }
  ]
}

[mattijn]

Run into this issue as well:

I found out that when adding a temporal tooltip the outliers are placed on the right places and not on the Jan-1970.

{
  "$schema": "https://vega.github.io/schema/vega-lite/v3.2.1.json",
  "data": {
    "url": "https://vega.github.io/vega-datasets/data/seattle-temps.csv"
  },
  "mark": {"type": "boxplot", "extent": 0.5},
  "encoding": {
    "x": {"type": "ordinal", "field": "date", "timeUnit": "yearmonth"},
    "y": {"type": "quantitative", "field": "temp"},
    "tooltip": [{"type": "temporal", "field": "date", "timeUnit": "yearmonth"}]
  }
}

(had to reduce the extent to get some outliers)

editor-url

[kpm-at-hfi]

Following