I have been hunting this for days without success. I have many categories which users are free to post articles into, but there is one category I want to restrict to a specific role.
My Wordpress version is 5.3.2.
I am using "WPFront User Role Editor" for the roles. I have tried the plugin "Restrict Categories" but it doesn't work on my site. Shows no categories at all. I suspect another plugin is interfering with it because it works on another site. The "Restrict Roles" plugin is not supported anymore anyway.
Some code would be helpful, even if it were something on the new_post page to not display the category at all.
I hope that makes sense and apologies if I have not given enough information :)
Update 17 January 2020
Issue temporarily resolved after disabling plugin designed to hide categories on the home page. See my comment for more info.