doesn’t think folders are configured but they are

Just recently installed Kodi 17 on my old MacBook which is hooked up to my plasma tv.
My movies are on a NAS box which is mounted by the MacBook.

When I launch Kodi, it says “Your library is currently empty. In order to populate it with your personal media, enter “Files” section, add a media source and configure it.”

Well, I did that, and added 4 folders to the files section of movies. However, at relaunch Kodi still thinks my library is empty and doesn’t show anything under “Movies” in the main menu.

Somehow I managed to add 1 folder to “TV shows”, such that when I select this item in the main menu it shows me “Categories”, “Recently added episodes”, and “Unwatched TV Shows”. I have no idea what I did different here than at the other menu items.

“Music” has the same problem as “Movies”. I added my iTunes Music folder to the files section of the “Music” menu item of the main menu, but when I select “Music” it shows the same “Your library is currently empty…” message. When I “Enter files section”, I see two sub-menus: “iTunes Music” (the folder I added) and “Music Playlists”. In the first I find my local music folder hierarchy, standard iTunes, sorted by artist, album, then files. If I select a file Kdi plays it…

Same in “Movies” – I can “Enter files section”, then select one of my 4 added folders, then a movie file and Kodi plays it.

So – why doesn’t Kodi recognize that those 2 menus are already configured, and still thinks the libraries are empty? What can I do to make it accept that the files section(s) are configured?