Earlier today myself and my guild master were talking about recruiting, he was using his usual chat macro. Then I remembered the guild finder had been added to Cataclysm. While I was setting it up the gm was talking to someone interested in joining.
Not long after… I had posted the guild up on the guild finder and the gm went to recruit the new member. The invite member button just didn’t work. I told him to try /ginv and that came up with the wrong command thing where it tells you to type /help. So I gave it a go, same result. So I had a random thought and took the guild off Guild Finder and told the gm to try again. He was able to invite the new member.
TLDR The Guild Finder is somehow blocking all ways of manually inviting someone to your guild when you list it.