I just upgraded to Windows 10 and faced this issue.
You could have StartWatch run without Admin rights and it would be ok. However I also use it to start and monitor Blue Iris webcam software where I need that to run as Admin hence I need StartWatch to run as Admin.
The problem is that Windows will now not autostart an App with Admin rights, it is not just StartWatch.
The workaround is to setup a Windows Scheduled Task that launches the app with elevated privileges at logon.