Also see this thread:
https://forums.elderscrollsonline.com/en/discussion/636786/pc-eu-the-seekers-archive-quest-bugged#latest
I suggest submitting a ticket via the in-game menus.
I submitted one for PC/NA and referred to the thread linked above. After the initial auto-response, and a few scripted responses, I was told on Oct-21 that the ticket was being escalated. I have not heard anything since.