OK. Here's the situation. On my fourth attempt, I'm many years into a game with a small-ish map, and doing well. I own about 70% of the Galaxy. Tech level is high. Pirates wiped out. (Including legendary ones who appeared twice.) Some smaller Empires absorbed.
Yet no Shakturi.
I've read other threads on this subject, and - correct me if I'm wrong - there are a number of possible triggers for the Shakturi to appear:
A) Tech level of 5-6 (I imagine I'm there) and/or the average tech level of the empires is 3 or 4 (we should be there)
B) Most of the galaxy is colonised (we're there, for the "good" colonies)
C) A "third warning" about the Shakturi... I only received one from the Guardians. I think I might have dug up some info on them from ruins or derelicts or whatnot. Do they count as warnings too?
Looking elsewhere, I see there is a dark beacon or something that I need to trigger. I have searched every ruin, but other than trying (so far unsuccessfully) to rebuild a world destroyer, I haven't bothered to refit any other ships. Nor have I gone chasing after info at position abcdefg, hijklmn or whatever, when I'm pointed in that direction.
I assume the lack of Shakturi is due to the last factor?