Hello @Jörg Walther ,
Thanks for your query.
1.you might retrieve new icon by manually deleted the cache files on the RD Web Access Server: C:\Windows\Web\RDWeb\Pages\rdp (default location). Delete all files in there and then try accessing the website again. This should force the web server to refetch all settings from the app server or connection broker and the associated icons.
https://social.technet.microsoft.com/Forums/ie/en-US/7bd4fd12-4772-429b-aafc-b8046c540a37/remoteapps-on-web-access-page-not-updated-after-user-assignment-change-refresh-has-to-be-forced?forum=winserverTS
2.Did the issue occur before Windows update? What about reinstall the Web Access role on the stand-alone server and check if the Web Access publishing function is the cause? Please also refer to the following post for further troubleshooting: https://social.technet.microsoft.com/Forums/windowsserver/en-US/288aa3c4-1f72-4842-82d8-d1da5ef0c049/server-2008-r2-remote-app-web-access-suddenly-apps-are-gone
Best regards,
Leila
If the Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.