After using the app and going back into the app a few times, I will allow it to sit in the background. When I try to open it back up, I am presented with the app asking to enter my pin, I enter my pin and it looks like it will allow me through, then it reverts back to the home screen. The black in the video is me entering my pin. Only way to make it work, is to clear the data in the app or reinstall, a restart doesn't help. See attached video.
Nexus 6 - 5.0.1