Unable to set content of video sources after cleaning library

I’m in the process of installing a clean build of Kodi v17 on Ubuntu 16.04. I was making good progress when I decided to run ‘clean library’ to get rid of some missing files. It warned me about deleting things and I ignored the warning as I figured I could just add everything back if it deleted everything (which it did! Network server took a brief holiday or something?).

Anyway, I decided to add my Movies and TV Shows folders back in the file manager but after adding them I am not given the usual set content type window. I am not able to do this in the context menu of the source either.

Googling around this issue there are a lot of similar threads but none of the solutions have worked for me. It is apparently often a skin issue. I was using the Mimic skin at the time so I switched back to Estuary expecting my problem to be solved but it persists.

Any suggestions appreciated.