Is Cron enabled in your managed websites? Now it's needed to launch task. You can get more info about what's happening in logs; now there is a complete report there for every site:
There is a redirection; try changing site name to ...tirol/index.php/de.
If this doesn't work please send me administrative credentials to access to the site with control center and any of the sites with issues. Use the email from which you receive forum notifications.