A course has the access control B/ (owner only).
If the course is published step-by-step, the course can be added to the catalogue directly. As long as the access configuration is not open, the course is not shown in the catalogue. As soon as the access configuration is open, the course becomes visible.
This behavior should be the same when you want to add a course to the catalogue in the course settings. --> add this option in the course settings, so a course can there be added to the catalogue, also when the access control is for owner only.