As I haven’t found a solution for my problem after some research, I’ve decided to post it here.
Matomo is tracking the visits of or websits just fine, but the data is loaded in the widgets onla after one day. Although the live data ist tracked immediately. I’ve allready configured a cronjob, which is running every hour. Did I miss some configuration? Another interesting fact, is that the widget which shows, when the users did log in, works fine.