I'm having the same issue. I jumped on twitter and tweeted at Comcast Matt. I just did that now, so I'm not sure when I'll get a response, but I have a sinking feeling that they pulled the plug on HBOGo in favor of the Xfinity app which I wouldn't mind if I could use it with my Apple TV or Chromecast (and get current shows like Vice), but their app doesn't stream to either. Thinking of cancelling my coverage if this is the case.
I'm having the same issue. Been working with Tech Support (including App Support Team) for a few days. No resolution as of today.
No matter the platform, none of our accounts can authenticate with the HBO Go application, but I can use Xfinity TV Go to watch HBO shows and I can use the SHO Anytime app succesfully. I reached out to HBO and they said the problem was with the Comcast Xfinity Log In page.
It is very possible that there is an issue with the account permissions settings in the Comcast database. Comcast recently changed account numbers and even billing dates so I suspect some kind of database error.
All is well that ends well. I was able to log in to HBOGO today (11/19/14). Don't know how Comcast fixed the issue, but I suspect the recent billing changes in the Philadelphia area may have affected the user settings, permissions or other database entries. I will test HBOGO on AppleTV and on the desktop later today and will call back to report my findings to the great Comcast App Team Representative in Colorado that was the most helpful.
3 years later this is still an issue! I have tried changing my comcast password and username which worked once and now we're back to being redirected to the xfinity page instead of HBOGo! I'm considering cancelling hbo with comcast and getting HBO now.