The
Plugin Settings menu option should appear if there are any Spawner namespaces that end with the string
[:.]sitesettings. This
should be getting added automatically once the container service plugin is loaded for the first time, but you can check with a simple REST call:
["containers:projectSettings","containers:siteSettings","dqr:projectSettings","dqr:siteSettings","filesystems_plugin:siteSettings","ohifPlugin:siteSettings","siteAdmin"]%
If you see any *:siteSettings entries in there then the Plugin Settings menu option should show up and the question is why it's not doing that. If you don't see any *:siteSettings entries, then the question is why those aren't getting created automatically.