iTunes doesn't shows musics in iPhone

Hello i get iphone 12 mini and transfer all data from my ex iphone 7 include musics(mp3) . I had transfered a lot of mp3 to iphone 7 by iTunes. And i could see every mp3 in iphone7 over "device>... 's iphone>musics" part of iTunes. Now i can listen all musics(mp3 etc.) over iphone 12 mini but i can't see or listen none of that musics over iTunes. It looks like empty. Could you give me advice?