Making Course/Offering hidden for all except assigned learners

Summary

Looking for a way to make a course hidden/unsearchable for all learners except those who it is assigned to.

Content

I remember there being a "secret course" button but I believe this has been removed as I'm unable to locate this option.

Hoping there's a way to have a course unsearchable and hidden to everyone except for those it is specifically assigned to as learning. 

If anyone has any suggestions that would be helpful!

Thanks