Hierarchies are derived fields in your dataset that provide drill down capability when using visuals like bars or lines. For more background refer to this how-to article: Hierarchies vs. Drill-into when drilling down into your data
Sorting the values in hierarchies can be done the same way as other fields in your dataset by using “Order and Top K” field properties:
In our example by ordering in “Ascending” we ensure that as we drill up & down the hierarchy the x-axis values always appear in proper order.
Here we have drill down into month=6 and we see the day axis in ascending order as well.