I don't think the question is where, the question is why. Why isn't he with the parent team? It's got to be frustrating for him. He came up, played well, was instrumental in some wins, and got sent down. While I know he's not the first player to be on the Merloni Express at the same time he'll be 27 in just over a month.
The bright side for him is that he may be the heir-apparent to 2B for the 2020 team. Sometimes a player is just in the wrong spot and it looks to me like that's where Marco is now.