CCM cannot load link to DNG artifacts

 To link an work item with a DNG artifacts stopped working a week ago. If I try to set an an Affects Requirement or Implement Requirement to selection window appears and you can select to DNG project. In the next step will no content will be shown in the window. It's still possible to select one of the module by searching one and in the section for the artifacts a text Loading artifacts... appears but than nothing will happen anymore. I waited nearly 30 minutes with a small module but there was just still the text Loading artifacts...