Pope Gregory the Great, did not believe Maccabees was scripure
I read up on this, and the problem is an equivocal use of the term, "canonical." The Church did, and does, consider the "deuterocanonical books" of the Bible as the "second canon," just as the Epistles could be said to be held in lesser esteem than the Gospels, even though both are part of the canon of Scripture.