Unable to change visibility on project I own

Hi there.

I am trying to change the visibility of a project for which I am the owner to Internal or Public. The project belongs to a Group that is set to Public.
When I go to the project Settings tab, and expand the Permissions section, I can see the Project visibility option set to Private but the drop down is disabled. I can’t change it to anything. Any hints on what I should be checking to change it?