At first I couldn't add categories, having an issue like in this topic. I managed to override it by simply hitting enter instead of clicking the add category button.
However I'm having a similar problem with adding a Custom Field when writing or editing a page. I make a selection in the drop-down menu and add text in Value field, then hit the button Add Custom Field, nothing happens, the fields just clear themselves, the same is with hitting enter, it seems nothing can override this bug.
Please help me!
I can't downgrade, because it would be too difficult for me, WordPress is 1-click install on my host.
Taking away 'www' doesn't help either.