I have the same issue. On Windows I get the same reply as soon as I want to verify my account in the app.
And this is only the verification, I'm allready logged in on the app, but I wanted to make a change regarding photos that I backup on the cloud, but I can't do that as I can't verify myself. I get a notification on my phone if I want to trust the connection, and then get the numbers to put in the verification box, but then get the reply that it failed to create the PI. When I press OK I get back to the previous state where I am prompted to put in my password again.
I'll try to delete the app and re-install it, maybe it will let me update the settings then, if not, I'll go with another back-up service for sure. 