Video Sources Menu Items Missing

I cannot see my list of video sources, or add and delete them, or browse them because the menu that presented those options is missing. I’m having the same problem on two independent installations, one Android and the other Linux. Files in all the sources are still indexed and viewable via browsing movies and TV shows, but I cannot browse by source because I can’t find the list of sources. Under Videos/Files and Video/Library I see the same sub-menu. There used to be two different menus there but now, the same menu appears in both places, and it contains only these 8 items:

Movies
TV Shows
In progress TV shows
Recently added movies
Recently added episodes
Files
Playlists
Video add-ons

I can’t remember the exact contents of the missing menu, but it allowed me to descend into the directories of each source and see a list of the files there, add new sources, etc.

This isn’t an issue related to System/Settings/Appearance/File Lists/Show “Add source” buttons. That option is enabled.

I could not find a sticky post that says what information I should provide about my systems, so the following is my best guess:
Linux laptop system:
Build: Kodi 15.1 Git: (unknown) (Compiled: 15.1+dfsg1-3)
Skin: Confluence.
Android media player:
Build: Kodi 16.1 Git:2016-04-24-f6ceced
Skin: Confluence

One thing common between the two systems is the recent installation of a banned plug-in.
It’s been a while since I tried to browse by source, so I don’t know when the menu first disappeared.
I’d appreciate any clues that will help me track this down.