Meta (lemmy.one)

I was under the impression that, due to the nature of ActivityPub, that Lemmy and Kbin are interoperable. I've been trying all day to sub to something a fedia.io. I can see it on the list of federated instances here but the search always comes up "no result".

I'm able to subscribe to other communities at other Lemmy instances (with some patience).

Is there a difference syntax I should be using?

Thanks