No Boss

I know why i can not found the boss before at the youtuber boss location. The boss was born at the last five seconed of the dougeon time, so i can not find boss else where. The spot is right, but the spawn time is not. The boss might pop very late at the boss spot i know from youtuber. I have seen this situation twice, once at the first floor, seconed at the seconed floor. So this is a bug, i believe. The boss should not pop up so late. I do not think is there any player could finished the boss in five seconed. This situation is the same as there is no boss. And this event is nearly over, but i did not get any blue items from it, so sad. Good luck to me.