Track listing goes from the Roche battle theme to queens blood (boat) tracks so, not looking good for your song being on OST. Ideally it's a repeat from Remake or Intermission? Otherwise would need to wait for Plus soundtrack.
Ok just pulled up someone's stream and I dont recall this song pre-Rebirth so yeah, unless it's out of place on OST, going to need to wait. Whenever I listen through soundtrack I'll keep an ear out for it.