Just be persistent because they can complete the quests for you. I faction changed from alliance and couldn’t continue the talador questline because the NPC was phased so they put me one quest ahead. The issue wasn’t solved, they just circumvented it.
On the other hand, it was impossible for my void elf to complete the Vash’ijr questline because of the NPC in the caves who wasn’t there. They couldn’t skip it for me then, I had to leave the zone completely. I’m betting this bug is probably also still there.