[I'm sorry if my English is not good ]
Some days ago, I still can login to Intel App Preview on my Lumia 520 ( Win Phone 8.1 updated ) , but now I can not do this, when I login to the app it halt at authenticating process. I don't know the reason when ( because my network or anything else...) , I tried it many times but didn't succeed. I still login XDK successfully on my PC. Any body here have the same problem, please help me! thanks a lot.