Penance quest not working properly

I've just finished A Distant Storm and suddenly Penance is part of my quest list. I don't remember getting any notification about it or dialog, and when I track it nothing happens. I've found where Alma and Ri'nela are beside the burial mound but I can't trigger any dialogue or cutscene. I don't remember doing this mission in my last playthrough, so I don't know where I've gone wrong. Has anyone else had this happen?