How does this work on kbin at the moment?

My understanding is that, at least on Lemmy, you should be able to search for a full community name, wait a while, and have it show up and start federating. I've been searching for two communities (in the format [email protected]) on kbin since yesterday and it still shows no matches.

Both are small (<20 subscribers) and currently inactive (no new posts in a week). Do I need to wait until there is new content in them?

So I subscribed to a Lemmy community earlier, and according to the site there are three subscribers to that community here on Kbin, yet content is not showing up here.

Original instance: https://sopuli.xyz/c/progmetal/data_type/Post/sort/New/page/1
Lemmy.world: https://lemmy.world/c/[email protected]/data_type/Post/sort/New/page/1
Kbin: https://kbin.social/m/[email protected]/newest

The former two seem identical as far I bothered to check, with 10 posts in the past 20 hours, but Kbin only has one of them (and it's not the oldest or the most recent, either, but the second oldest).