Hi Robert,
I just chatted with one of Capture's engineers about this. He said that the sign in screen comes not from Capture but from Adobe's main Adobe servers... and that this blank screen seems to indicate that you're, for some reason, not connecting to that. A couple of things:
* Where are you located?
* Are you having any trouble signing in to any other Adobe apps?
* I can see that you have a full-strength signal, but I notice sometimes with my Android device that my signal can be strong but I'm still not connected. Have you tried a different wifi network?
Let me know.
Sue.
To answer your questions I am in Portland, Oregon. And I have not had any trouble signing into my Lightroom CC or Acrobat app.
But I actually got it solved by pressing a few buttons randomly. I kept moving the app into dual app mode, to full view mode, and back and forth till the sign in page showed up. Weirdly that's what solved it. Thanks for your trouble!
Robert