No problems for me (iOS, CCHD).
Try deleting the game and reinstalling. Actually, I think I can probably just copy/paste what support will copy/paste you.
Thank you for contacting Support. Please try deleting the app from your device and reinstalling the app from the app store; you will not lose any game progress and that should clear the issue. If you are still unable to log on afterwards, please reply to this email and let us know.
Happy gaming with us!
And just FYI, when following their instructions makes zero difference, telling them so will be totally pointless. You will just get this response:
Thank you for contacting GREE Support. I apologize for the inconvenience caused. In order to solve this issue, I request you to update the newest version of the Game, please try deleting the app from your device and reinstall the app from the app store; you will not lose any game progress and that should clear the issue. If you are still facing issues, please reply to this email and let us know.
Regards,
Aaaaand repeat loop on broken record.