This drove me mad last night, here’s the way I fixed it, deactivated all the Plugins, Logged into the database using Navicat, you can use PHP admin, view the oprions table, on line 59 is the DB version, change this to a previous version (5183) then run the wordpress upgrade url (https://example.com/wordpress/wp-admin/upgrade.php) ang guess what, all my categories came back, I can add, edit, and delete. I also installed the stickey category plug in and that works.Good luck
