I thought that as well but two things kept me from believing it was waiting for content or a new post.
First the missing category is showing up in the dropdowns at top left and in the tag bubble on the bottom of the menu.
Second it has a sticky post which I assumed would count as content/post for purposes of avoiding having a new category be completely empty upon its creation.
All of that said… when I created a New Topic in the missing category it immediately showed up in the /Categories page.
and now on to defending my ignorance.
[quote=“codinghorror, post:6, topic:23898, full:false”]
read the category edit dialog[/quote]
I went back and looked again at the Add New Category and Edit Category tabs. I am probably missing something obvious but I did not see any validation issues when I create or edit a category. And there is no help or other info suggesting I need to create a post in the new category before it will show up on the /Categories page.
[quote=“codinghorror, post:6, topic:23898, full:false”]category definition topic…[/quote] Is this a discussion here on meta or a help section within the discourse install that I missed?