This video is from last time I posted about this, but this issue still occurs (in the same way) after 3.0.1 and the result is the same as in the video. The Essence of Servitude Quest (necessary to obtain the 'Harbinger' title) cannot be completed because the Major in the Catacombs does not spawn in order to get the quest item drop. I have even tried abandoning the quest and picking it back up at the Tower.