Guild War's works, so I can say, Hi there but can't congratz to a friend on a new boss? Sometimes you (KANO) just blow my frigging mind on things that you do.
lol!! My theory is they've placed a blanket ban on you for all 'public' messaging within the game...they can't control that guild wars bit as it's provided by facebook itself. lol this is a first time i've seen this...can you comment in your own bosses? if so try turning on public sharing for the boss and see if it still lets you. Kano are out of office till tuesday so experimenting is the quickest way to get answers
Unfortunate Jades this is correct being banned numerous times myself from world chat. You do get banned in all other forms of communication within the game also.