Trying to redo the quest 'The Only Lead' using the 'Reverie Incense: Bloodmoss' item.

Portaled into the zone but Illthain did not appear. The quest marker points to where he should appear, but he does not show up.

I can neither go forward further into the map, nor town portal out, leading to me having to return to the main menu.

Have restarted the quest again using a second Bloodmoss item to double check, and the same thing happened again.
https://imgur.com/a/2b1u0qS