Although it had been fully written and recorded, the series dropped off the radar around the same time that Netflix cancelled a number of in-development animation projects, including adaptations of Bone, Wings of Fire, Antiracist Baby, Pashmina, and a Jamie Hewlett-directed Gorillaz film.
Probably a good thing considering MtG's fluff has been shit for years. They want that Marvel money and have been doing "theme parks with hats" settings now for over a decade.