Apparently, the Lollipop update for the 8.4 has only been released in Korea. It's been roughly 3 weeks now. As an 8.4 owner myself, I've become fairly impatient now (and that's putting it lightly), but there isn't much we can do.
To summarize, 8.4 update only in Korea. No evidence of it rolling out in North America yet... (I'm in Canada).