The Professions filter works by filtering data from practitioners who are tagged with that profession (which pulled from their Cliniko practitioner delegation).
Example
Q. When you use professions as a filter does it pick up all the revenue from classes that that profession took? For example, if 14 out of 20 pilates classes were taken by Profession: Physiotherapy and 6 were taken by Profession: Osteopath.
A. Yes. If you filter with Profession: Physiotherapy, and there are 20 pilates classes in total and 14 were hosted by practitioners with the Profession: Physiotherapy, then only those 14 classes will be accounted in the metrics calculated.