Bar stack order does not respect domain order when based on colour channel

[claresloggett]

Bug Description

If create a bar chart, and set the color channel to a field, I will get a stacked bar chart like so:

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {"values": [{"category": "Cat1", "status": "Present"},
    {"category": "Cat1", "status": "Present"},
    {"category": "Cat1", "status": "Missing"},
    {"category": "Cat1", "status": "Present"},
    {"category": "Cat2", "status": "Present"},
    {"category": "Cat2", "status": "Present"},
    {"category": "Cat2", "status": "Present"},
    {"category": "Cat2", "status": "Missing"},
    {"category": "Cat2", "status": "Missing"},
    {"category": "Cat2", "status": "Present"}]},
  "encoding": {
    "x": {"aggregate": "count"},
    "y": {"field": "category"},
    "color": {"field": "status",
      "scale": {
        "domain": ["Present","Missing"], 
        "range": ["blue", "lightgrey"]
      }
    },
  },
  "mark": {"type": "bar", "tooltip": true}
}

Open the Chart in the Vega Editor

Here I have set the domain of the colour channel. The order of the values [Present, Missing] is reflected in the legend as a result. However, the order of the stacked bars themselves is unchanged. The order of the stacked bars will always have "Missing" nearest the axis, regardless of domain order - presumably it is ordering the values alphabetically. In this case I would like "Present" to be the bar value nearest the axis.

Is this expected behaviour? The docs I found said that the stack order defaults to the stack grouping field, so I would have expected setting the domain on the channel to affect the default stack order.

Checklist

- [ x] I checked for duplicate issues.

[MarcBaeuerle]

Here is your fixed version

Documentation