Same problem here. It's actually doing the auth correctly, it seems, because I then went to the main home page again and it showed me as logged in, and I could get to my dashboard from there.

Didn't went that far, simply revoked access on my gh account.

I probably would have done the same if I hadn't already used it in the past. But it's worth checking out again. I tweeted support to let them know.

Ops, that was a mistake on our end, just fixed for everyone. Sorry!