For those who are unfamiliar with the the Lord of Light, he is a god who has speaks to his followers through visions. As Forbes pointed out, in season 7, episode 5 "Beyond The Wall," it seemed that the Lord of Light specifically ordered The Hound, Beric, and Thoros to face the White Walkers, only for them to fail. Not to mention, Bran sends Jon Snow a raven telling him that the Night King was coming and sending him beyond the Wall. Perhaps Bran, a.k.a. the Lord of Light, saw that the Maesters would ignore his pleas for help and from his various timelines sent all the help he could.