In Opportunity entity, user has created the custom fields e.g. Service (lookup field) and Type (pick list)
When create a Top 5 chart by choosing the Lookup field (i.e. Service) as Horizontal Category, the chart appear sorted.
But when choosing Pick list (i.e Type) as Horizontal Category, the chart appears unsorted

This happens to all Pick list fields.

Even though the data selected to show in top 5 is correct, it would be better to make sorting correct and consistent in all type of charts