DarkoD13: I tried this since I'm having the same problem, but now nothing happens when I press on the "more" button or the notifications.
I have the same problem. I had to switch to using a bookmarklet to fire off the code on the page.
The bookmarklet code is this:
javascript:var%20result=PresentGroupInviteOptions();
Just use that instead of an address for your bookmark. Then when you click, it will bring up the invite box.
I also let support know that this change fixed my problem. They said they'd forward the information, but I haven't heard anything more.