Hi,
I'm afraid that's not possible.
You can arrange the values in the bars according to the labels of the option set fields.
However, it is based on the alphabetical order of the label text.
In my testing, I created an option set field.

Added these two lines of code to the XML of the chart to sort the bar values in positive order based on the label text of the option set.
In the chart, records with the option set field labeled Empty (None) are in the first group, after which they are sorted into groups based on the alphabetical order of the label.
Therefore, if all of your options begin with the letter V, the records will all be in the same group.
Whereas before it was sorted by the value of the option set, now it is sorted alphabetically by the text label of the option set.
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If you have further questions, please feel free to contact me .
Best Regards,
Dengliang Li