I tested my query serveral times by sending an invitation to my own address.
When I start the query, the query does not start at the very beginning, but from a point serveral pages further.
I thought, could be a problem with cookies, that have been set. But deleting all the cookies, the problem stays the same.
(Running the query in the Question-Editors preview, everything is fine!)
Would be glad to get some hints! – Thank you very much!