WordPress might not be showing your Custom Post Types and Custom Taxonomies on the Menus screen for a really stupid reason

I’m working on a new WordPress site that’s going to have both custom post types and custom taxonomies, and I want my custom taxonomies’ archive pages to be in the site’s navigation menu.

Seems like it should be easy, right? If you set show_in_nav_menus to true in register_post_type() or register_taxonomy(), you’re supposed to get access to add them to your menus.

But when I set that, they still didn’t appear on the Menus screen. What the…?

I found it exceptionally difficult to track down any information about this, although I did eventually find a tutorial on the very subject but… whoa, those are some old screenshots! The tutorial is a decade old.

Nonetheless, I proceeded to try to make it work, with extensive customizations to suit my needs. Strangely — and it should have been a clue to me — they wouldn’t appear if I gave the meta boxes the name of my custom taxonomy, but if I gave them an arbitrary name, it did work. But there were still some quirks, so I started digging around in the inspector to figure out what was what. Then I discovered something really odd.

They were already in the page. Only, they weren’t displaying. That’s because they all had a CSS class hide-if-js applied. So what’s that all about?

Well… it was really stupid. They were “unchecked” under Screen Options. You know, that little tab at the top right of every WordPress admin page.

My best guess here is that it’s because I had already been to the Menus page for this site before I started building the CPTs and taxonomies, so when I added them to the theme, my personal preferences for Screen Options on the Menus page had already been set, and therefore they defaulted to “unchecked.”

That seems kind of stupid. More specifically, it seems stupid that WordPress gives you the option to turn the items in the Add menu items list off. But it definitely should default any new items that suddenly appear, i.e. that are not already “on” or “off” in your preferences, to “on.” So you, like, know they exist.