white raven markers not appearing during challenge

@huyness6 I think you just did not move over the hill to see the next ones. For me, Raven appeared in the Lava Syphon part and lead me through the tunnel and closer to the Dome. Markers were appearing but indeed the distance between them was slightly longer than usual tracker markers you see of enemies passing by. So sometimes I just had to use logic and move in to current direction without seeing a marker.