I don’t know what causes this but this has happened to me in the past. A re-install did not fix it because the problem is with the plugins which are shared among all Sonic Foundry products so if the install program sees the plugin, it won’t re-install and it stays broken.
What I had to do was uninstall ALL my Sonic Foundry products, and DELETE the \Sonic Foundry\Shared Plug-Ins\ directory and all registry entries for Sonic Foundry. Only then did a new install clear up the problem. Hope this helps.