I have the same problem,its worked perfectly before the update, now i cant sign in and have tried on numerous occasions for the last 2 weeks. I followed the link on u gave and cleared my cache and reinstalled (tried this twice) It just wont let me sign in, i enter the username and password then when i press the sign in button .....nothing, the cancel button next to it works?
Thanks for getting in touch. Do you have any special characters in your username and or password? is so and there in the password can you change this so that only numbers and letters are in the password and try signing in then?