kde5/6: recent files/recent applications

Hi *, the problem already existed in kde5, but continued in kde6: The menues for "recent files" and "recent applications" stay empty in the start menu, in dolphin and other apps. In .local/share/RecentDocuments/ all the desktop icons for recent files are still existing. The list is updated whenever I open a new document, but nevertheless the "recent files" menu remains empty. As for "recent applications" I can't even find a folder, where they would be stored. I found a few, mostly very old postings on the net, but no fitting answer. Anyone any idea? TIA. Bye. Michael.