Chapter 2, “Luther in His Early Period (1517-1524)” - Part 1 - The Source of Luther’s Doctrine on the Lord’s Supper (p. 62).
Sasse observes (p. 62) that the Lutheran Reformation and its work with the Lord’s supper sprang from Medieval discussions. Possibly even without knowing it, the Reformers are influenced by their backdrop. Luther arose as the great theologian and liturgist of his time.
While Luther didn’t deny the real Presence, he did say that celebrating a Mass without communicants, as was the Roman custom, was not appropriate. As early as 1519 he was writing about communion and, even in that early time, affirmed the Real Presence and that the body and blood of Christ was distributed to communicants.