Experiencing the same issue as Eric. If it means anything to you - the origin I’m trying to connect from is localhost (http://localhost:33006), and I’m trying to connect to Trello via my Google account that I have a couple of trello boards with, and I’m using the latest Chrome.
Authentication goes fine, then I end up at the blank 1/token/approve page.
Yes, the html looks as you described.
Something in particular you would like me to check regarding the window.opener object?
Edit: Okay, so I’ve just tried registering a new Trello account with an email/password directly (i.e. without using Google’s API). I also tried changing my hosts file so my localhost origin looks like my production URL plus port. Same thing happens, regardless.