The friendly mechanism for adding categories on the mobile site is to tap the categories button and then "add categories." However, the initial categories button is not shown for pages which presently have no category memberships. This behavior doesn't encourage users to add categories to the pages that most need them and should be fixed.
Steps to Reproduce
Create a new page
- The categories button is shown
- The categories button is not shown
- Minerva mobile site
- Chromium 69.0.3497.81
- Ubuntu 18.04
Category adding by people who don't know exactly what they are doing is probably not something we want to encourage and one of the reasons the feature has been in limbo for so long.
Also adding categories is subject to a lag (T163121).