Not possible to change public/private after uploading?

After a Contributor has uploaded an item and checked or left unchecked the “public” option, how can that private/public detail be changed afterwards?

As the Admin, I can’t change it, I get a message that the Contributor didn’t want that.

If the Contributor logs in again and edits the item, they can’t see anywhere to make it public or remove it from public either. It’s as if that property can only be set once and then it’s gone?