What is the logic behind which SUBGENRES that will show on top of title page alongside with GENRES?

Hello.           On the movie "The Hook" https://www.imdb.com/title/tt29204860     I  added on #250929-185820-806000     Genre: Music         then after      on #250929-190113-201000           I added subgenre: rock-music         But the "rock-music" is only listed among the Keywords down on the page.        It is not "on top" alongside the other genres/subgenres.                 I also added subgenre: dark-comedy  #250929-185034-766000            But that subgenre did also end up on topp of the page.               Is there a logic here to which subgenres that will be showing on top, and which will only show as a "keyword" down on the page?            Or is there an error/fault her in the system?               Did not find any info about it here:                https://help.imdb.com/article/contribution/titles/keywords/GXQ22G5Y72TH8MJ5#subgenres