I vaguely recall there was a way to hide issues from certain roles based on category, but I can't remember how to do so (or quite possibly, my memory might be wrong!)
My goal is to be able to lock an issue to the internal dev team only, and have an indicator on the page that it is locked. I have been experimenting with Issue Access Policies, but it doesn't display on the issue view page anywhere that it is locked unless you open the submenu. Category method provides a visual indicator, but I don't recall how to set it up (if it was possible to do so)