Label name in charts

I'm developing a Help Desk application and need to create a column chart for priority. When a priority is clicked, its ID should be stored and passed to a drilldown grid but the current code is displaying the ID as the label instead.

 a!grouping(
                          field: 'recordType!HD Request.fields.priorityId',
                          alias: "priorityID
                        )

If I use 'recordType!HD Request.relationships.priority.fields.value' directly in the field, it throws an error.

Any suggestions on how to display the label name?

Thank you!