Deborah Chow told Holt to compose as though they're not allowed to use JW themes, because they are looking into it.
JW is brought in to compose Obi Theme, and William Ross is given the okay to use themes, but only in the last episode.
Doug Adams implies yesterday on Twitter that withholding his themes in the Obi Score is consistent with JW being unhappy with Giacchino using his themes on Rogue One, which was then quickly rescored.
Doug also implies that that's why Williams took greater interest in Solo, after not being asked to score Rogue One himself.