Minecraft crashes trying to sign-in to Xbox Live

I had to reinstall Minecraft PE on my sons iPad and now whenever we try to Sign-in to his Xbox Live account, Minecraft PE crashes to the Home Page as soon as we click the 'Sign-In' button. As a result we are unable to play on his Realm Server using this device. All my other devices are working as I have not signed out of our Xbox account so they are still auto-logging-in. I am reticent to log out just in case we are unable to get back in.