In order to display the correct data in Statistics, you need to distinguish between the classic, i.e. main nursery classes, and other, i.e. secondary, classes (e.g. rings). Therefore, we have added a Main Class field to the class settings and for your nursery classes, select Yes in this field.
WARNING: At this time, you have a default setting of No for all classes. Until you turn this on, nothing will be displayed in your statistics.