I have a similar problem: We have a course category with subcategories for each department of the university. I want a person from the physics department manage categories within the physics category. So I created a new role "Category manager", set the capabilities
create/delete/update/see hidden to allow, all other capabilities to inherit.
Then, as an admin click on the physics category, use the link "assign roles" on the physics category side at the right/above corner and assign the person this new role.
Logging in as this person and clicking on the physics course category I indeed get a button "turn editing on". Now I am able to create/delete/move etc. courses in the physics category, I also can rename the category. But I cannot create a new course category as expected.
So what shall I do?
Thanks in advance.