Ref literal vs. label value in chart legend

[dbaum]

In my charts, the legend uses the literal value of the column being summarized (see following screenshot) even though the column is a reference to another table's key column. Elsewhere AppSheet automatically substitutes the referenced table's label column values for the literal values--e.g., when selecting a value for the column in a form, when using the column as a group header in a view.

In a chart view, is what I'm observing a result of something I'm doing wrong, a bug, or simply expected behavior for which I need to implement a workaround (such as adding the referenced table's label column to the table I'm charting, like is apparently necessary to Sort group headings by displayed value instead of reference ID)?