FlightXML2 SearchBirdseyeInFlight: “circles” behaviour

For method ‘SearchBirdseyeInFlight’ the documentation states a query filter like ‘{> circles 3}’ should work, although it is returning no results.
I can return results for many other query filters and even found flights for matching filter {= circles 0}.

The issue is, I would expect some flights globaly within the last 24 hours to have circled more than once, which the data is not showing.

Where am I going wrong?