I would like to add my bits the cause.
It seems it used to work before when i was using the default passphrase, i.e. my account password. Since i changes the default passpharase from the desktop version to a new passphrase, the Sync stopped working. I think for Sync to work in Android and mini versions, we need to use the default passphrase (account password). If the developers add a form to fill the custom passphrase, it might work. These are my thoughts, have anyone of you experienced the same?