It’s not app specific - that’s just how the Lemmy code works at the moment.
For this specific reason, Lemmy integrated search feature is fundamentally broken at the moment, so you should be using https://lemmyverse.net/
When I first joined my instance I couldn’t see any Xbox communities so I created one. It got a little following, but then I found out there were already two communities literally called Xbox but no one from my instance joined before, so I couldn’t see them.
It’s very early days of Lemmy so there is a lot to sort out but the community is great 😃