Cross-Report-drillthrough not working

Hi, 

we were checking out the new Cross-Report drillthrough on the Report Server May-version and prepared a report according to the official documentation. However, the target is not displayed when opening the drillthrough-context-menu. 

Did we miss some special requirements for the report-server-version? We couldn't find any documentation in the report server release notes, so we assumed that storing all reports in one folder would have the same effect as storing all reports in the cloud-workspace.

Thanks in advance.