I just realised sometimes you can't see posts from other instance's community if no one from your own instance has joined (or even posted/commented?). So I'm here from lemmy.world to say hello to the community, and also for users from my instance to be able to see this community.
From my understanding, the number of subscribers you see when you searched for the community only shows users from your own instance. For example, when I searched for !kdrama@lemmy.ml it showed 0 subscriber, because there wasn't anyone from my instance (lemmy.world) who had subscribed yet. Hopefully, now it would show at least 1, if anyone from world wants to sign up.
There were some discussions going on the lemmy.world's !kdrama@chirp.social community. But I realised that was a mastodon community where not only users from lemmy can't see the more active discussions on mastodon, but also ONLY users from the same instance (and apparently mastodon users?) can interact with each other. I created an account on another instance and it displayed a completely different kind of posts.
My thinking is that since Kdrama is still considered a relatively "niche" interest, especially among lemmy users, it would probably be best to combine our users for the time being, rather than having a handful of users on every instance who'd prefer to lurk but nothing to lurk about since no one's talking/posting.