Yes there are approved Marian apparitions that happened in the Middle Ages. Consider these - Our Lady of Walshingham (1061) in England, after Compostela one of the greatest shrines for pilgrimage, Our Lady of the Rosary (1208) appeared to St. Dominic to give him the weapon to defeat the Cathars, and Our Lady of Mt. Carmel (1251) appeared to St. Simon Stock to give him the Brown Scapular