Starting with this update, you can specify Ascending or Descending sorting order in charts using the Sort drop-down list.
By default, the value is set to None. However, for pick list fields, the None value is not available and the default is set to Ascending.
For the y-axis, the Ascending or Descending sorting order is supported for stacked and cluster chart types. The Sort drop-down list does not appear when the multi grouping checkbox is selected for the y-axis.
For boolean fields, the sort options are determined by the data model.