Well it looks like Facebook is doing maintenance on the groups, hopefully it's not the switch over, but that's probably what it is.. I have a feeling when it comes back it will be in the new group format (If at all..)
But for the mean time (or permanently) you can use the Finish My Operations Facebook App! No group to join, just simply authorize it so it can show up in your apps section! And you can start posting and finding operations now! It updates live so there is no reason to refresh! You might even like it better than the group!