When there are multiple dramas or movies with the same title, the topics in the discussion section all show up in the forum of one of the titles -- the oldest one -- and don't appear on the other pages. For example, if I try to post a new topic for the drama "Hidden Love" (2021), it will show up on the page of the movie "Hidden Love" (2020). It's happened to me with other titles in the past and it's quite a problem because it makes the discussion box unusable for more and more works as time goes by. Another example would be the title "The moment": the topic that you currently find on the page of the movie is actually about another series with the same title.
