WinCC OA Project Autostart
A user interface cannot be started (or will not be visible) when running the project as service.
The service is started when the operating system is started, even before is user is logged on and therefore you cannot start processes which are meant to be displayed on the screen.
Senior Support Specialist
Basically you cannot start an UI from a service (This is not a limitation from WinCC OA but by design from the Windows operating system).
The service is started before a user is even logged on, so a UI window cannot be opened.
One possible solution to autostart a UI would be to create a batch file (.bat) with the command to open the UI and put this in the autstart folder for the user that logs on (or use the Windows task scheduler).