[captain-normal]

I've configured sources. I've configured home menu buttons. But I'm at a loss how I can assign a source to each home menu button. (This seems like such an obvious thing, so I assume I am missing something obvious...)

In detail, in case it's needed: I'm displaying three buttons: Movies, TV Shows and Videos. The last of these is a custom button. I have three sources which have been successfully added - folders on a network share - called Movies, TV Shows and Videos. I'd like to access each of these sources from the correspondingly named button.

[nickr]

It doesn't sound as though you have scraped your files into your library after adding the sources.

[PatK]

Any source can be added to favourites from the context menu, The skin settings for the custom menu will allow you to link that favourite with supplied name on the home screen. (ensure your sources are functional as noted by @nickr)

[captain-normal]

Summary of the solution, for anyone else reading this:

Setting the content of each source to "None" to allow it to clean the (anyway empty) library for that source, then setting the content back to "Movies" and "TV Shows" and this time it scanned correctly. Reselecting the "Videos" source for the custom button also worked. The section "Refreshing the library" one the Wiki give a little more detail: http://kodi.wiki/view/Set_content_and_scan

I don't have much clue about why this did not work last night, as essentially it was just the same thing I did today. I guess there was a problem recording the information to the database. Repeating the setting of content step worked for me in this case.

A big thank you to nickr and PatK for solving this for me!