If the Seekers have moved to the Abandoned Camp before you bless the burning pigs, they will never show up at the sanctuary and you can't progress this quest. As far as I know, but I may have missed something. I looked far and wide to find where they ran off, and I was unable to find them after this sequence of events: (1) blessing the first burning pig to extinguish it, (2) killing Scapor who showed up at this point, and (3) blessing the remaining pigs I could find to extinguish them all; they all run off right after they are blessed before I can talk to any of them. There is intended to be dialog for you to send them to the sanctuary, and then they will ask you to do another task for them. Another factor may be that I caused a lot of explosions earlier that made them lose reputation with me; maybe I was too hated without realizing it, so they didn't want to ask me for more help. "We left Reaper's Eye without helping the pigs."