The review queue is a filter, which shows a list of questions with a certain criteria. The idea is not to show the entire list of questions, but only these which are flagged by a group member for later review. A look into the close-view queue have shown, that it's empty. That means, there are no questions which can be closed. Is this a malfunction or is it normal?
I think it is just because Robotics doesn't get that many questions. With only 2.1 questions per day according to Area51 (https://area51.stackexchange.com/proposals/40020/robotics), our few moderators can keep up. I don't know how many questions the "real" Stack Exchange site gets, but I'm sure it's a lot more.