How do use createSelectionIdBuilder correctly with multiple categories?

Hello,

When I select 'b' in the top row (first item), Sunday is selected in the standard pie charts (first item). When I select 'a' (second item), Saturday is selected in the pie chart (second item). This is despite selectionId correctly logging the table name and field name.

I have some test categories - Day of week, parentCategory and cutAcrossCategory:

There are 14 rows. ParentCategory neatly maps to Day of Week - so wherever we have ParentCategory = a, Day of Week is Monday, Thursday and Saturday. CutAcrossCategory, as the name suggests, is meant to disrupt this, so one of these categories does not neatly map to Day of Week.

I have a visual that uses a single number (measure) series, and n categories, and visualises the result as n bars, each split by their category items. I also have three pie charts, one for each category above, for testing.

When I click on a rectangle (one category item), I can see the selectionId is correct - the dataMap and Key show me the table name and field, and the value of that field. However, when I click the first item in parentCategory on my visual, the first item of DayOfWeek is selected in a standard pie chart showing DayOfWeek (this is Sunday). On the parentCategory pie, the Sunday portion of 'b' is selected.

                this.selectionManager.select(selectedId, multiSelect)
                    .then((ids) => {
                        console.log("Selected IDs after click:", ids);//logs correctly
                    });

Here is the logged object:

[
    {
        "deepestNodeLevelInPath": -1,
        "measures": [],
        "dataMap": {
            "data.parentCategory": [
                {
                    "identityIndex": 0
                }
            ]
        },
        "nodeIsCollapsed": null,
        "nodeIndexes": [],
        "key": "{\"data.parentCategory\":[{\"identityIndex\":0}]}[]"
    }
]

So the parentCategory[0] is triggering a DayOfWeek[0] selection in standard visuals. Can anyone help me explain why?