BPC 10.1 - dump in unified model when I try to open System Reports

Hi, we use BPC 10.1 unified and every time when try to use "System Reports" it dumps. I can select e.g. BPF Activity Report and Templates -> Template Verions -> Instances and finally "Display Report" but there is no result besides the endless loading screen. Is there a certain web Service that has to be activated first? Thx for any hint