I’ve had that happen to me too (the category thing). From what I know, you have to publish a post to the category for them to show on the admin screen (or the front page). Not a lot help but add a category, then switch to write post and with any luck, it’s there.
Has there been resolution on missing ADD LINK button – our search page went kerplewy, then the ADD LINK button went missing too. Would love to fix this, please advise. Our nonprofit group Accuracy&Aesthetics has 2 volunteers waiting to work on inputing links but suddenly unable to utilize their gracious efforts. Thank you.
If you have mod_security on the server, turning it off would be the only real fix.
I fixed this by going into myphp admin on my host, choosing the WordPress database, browsing in the wp_options.php and making sure the site url had “www” and wasn’t just “http://sitename.com”; I had to make it “http://www.sitename.com”