OFB-12

May I ask: how did Bishop and Dark manage to start playing the 4th round before the 4th round draw was published?

I'll say more: it's not just them, and this isn't the first, and probably not the last time in this tournament that players start a match before the draw is published. Most often, this is because one of the players cannot play for most of the round and asks me to provide an opponent earlier. Seeing such interest, I, of course, try to accommodate and find an opponent who fits the draw and is available to play.