Try going to the tiki-admin_system.php page and clearing out the caches.
Once objects are placed into categories they are governed by the permissions of that category. You need only apply permissions to individual objects if they do not match the category in which they are under.
If all you want to do is allow anonymous users to view and registered users to be able to view and edit, it doesn't sound like you need to manage permissions on categories at all. You should just be able to let categories use the global permissions as defined by your user groups. You can quickly identify those categories that have global permissions by the key icon next to them, yellow means global, green means custom/special.
I would personally reset all your categories to use global permissions and just focus on the user groups.