I've heard that purchasing gamepass sometimes doesn't work for some games. I don't know if they solved the problem, but once with Inquisition there was an error with the dlc if another user bought the game for another user as a gift and they didn't work in the game either.
The only thing that comes to my mind is that there may be a problem with DLC authorization and the same thing happened in Dragon Age 2. Try logging in to your EA account in the game's main menu. The same login to your account in Dragon Age 2 scanned and authorized the dlc
