The cause of this has been known for some time, it is the same reason that RoboHelp has never appeared on the Recently Used list through various versions of Windows. There's a short reference to this in Snippets on my site and there was a link to a Microsoft Knowledge Base article that confirmed all this.
Rick Strahl's comprehensive explanation is very useful as it does explain how someone can fix this on their own PC if they so choose. It's a great link, thank you for finding it and taking the trouble to register here and post it.
Welcome to the forum.
See www.grainge.org for RoboHelp and Authoring tips
Very useful information! After my hard drive had to be replaced and everything had to be reinstalled, we couldn't pin RH to the taskbar (it had been pinned previously, so not sure what happened). Now I'm a happy camper.
Awesome! Not having Robohelp pinned was driving me crazy.