The problem has been solved by updating to the latest version 188.8.131.52.
We use the FreeFlowCore server, and at some point I noticed that I can't define new active folders for IN. The server runs under Windows 2016 Standard with version 184.108.40.206.
The error I get when I want to define an IN folder is: "Data collection not possible: Error when calling the web service." (Translated from German)
Can someone help me?