born in darkness part 4 not showing up

[Hakuyru]

iv just completed part 3, and now the stage 4 isnt showing up at all, it didnt automatically go into my quest list. and the exo stranger doesnt even have it on her.
where am i meant to pick it up or how do i get it?

[fluffy]

Same problem here

[Zoomii]

I think you need to do the quest Legacy's Lament first.