This only happens with AK. It is simply a bug. Count the bosses. There are not four. It is clearly not intended behavior, and therefore not a legitimate game feature in need of a petition. Some programmer put a 4 where there was supposed to be a 3. That is all that this is. They're surely aware of the issue by now. Just wait for 2.1 to fix it. In the meantime, you can avoid the issue altogether with ease. Simply read your alerts before clicking the Join button. 3/4 = click on Withdraw. Not that hard.
(Or if you get that unlucky 3/4, then you might as well make the most of your bad situation. You can always click Join and collect the previous group's skipped gil coffers -- a potential 4k+ gil, minion, and level 60 accessory for two to three minutes of your time? It's better than a queue getting wasted for nothing.)