I created a custom post type in WordPress and registered it in my theme’s functions file. The custom post type works on the front-end when I manually enter the URL, and I can query its posts successfully. However, the post type does not appear in the WordPress admin menu sidebar, so I can't add or edit posts through the dashboard.

I have already tried:

Flushing permalinks

Disabling all plugins

Switching to a default theme

Confirming that the post type slug does not conflict with another post type

The post type does exist, because I can query posts and see them on the front-end. The only issue is that the admin menu entry isn’t showing up.

What settings or arguments could cause a custom post type to be hidden from the admin dashboard even when it is registered properly?