Two official facebook pages (Ninja Tracks, created by Kaveh Cohen and Michael Nielsen; and Michael Nielsen himself) that credit was given to two pieces of music for the trailer:

Michael Nielsen via Ninja Tracks
and Ninja Tracks claims other work done by Johnny McDaid, "This Is Not The End" (the last half or so that everyone likes).

Since we know McDaid is a self-titled artist and doesn't go by his studio name, Fieldwork, we can safely assume iTunes isn't managed properly.
I wouldn't trust any more what iTunes has to say about the "Jazz". It seems like the song is slumped into the Jazz/Contemporary categories in a very arbitrary fashion.

Fieldwork is the studio McDaid operates under.
Why iTunes would call it the "artist", I have no idea.


Could be a coincidence that there is a Jazz group named "Fieldwork" but it's not to be confused with Johnny McDaid of Snow Patrol and his studio in North London, Fieldwork ("Fieldwork Music" according to google).

Who knows, maybe all the other albums shown under Fieldwork may be just distributed albums from the studio and they all happen to be Jazz.