android:process=":sync"
As given in other answers works great.
On top of that, if your call to ContentResolver.requestSync(mAccount, AUTHORITY, settingsBundle) has anything wrong with it, your service won't get called without any errors thrown.
You need to double check that the Authority string is matching in the manifest and xml, and java code. Also the Account object is created correctly with the right account type and added to the AccountManager using:
accountManager.addAccountExplicitly(newAccount, null, null)
(the variable names are named after the official android tutorial here: