The B ranks were different at the start. I don't know what it was, I wasn't able to unlock the hunts when they first came out. But I do remember taking on those B ranks and the chaos that was going on with them with the crowds of people. I remember the fights over Naul in CCH. Then I think at the next big patch they changed something, the B rank went to a friendly icon and I could no longer get seals if I took it on, until I unlocked the hunt.