Scenario: a magazine "M" is hosted on kbin.
User "A" on an external instance (specifically Lemmy, I'm unsure if this also happens when this external user is also on kbin) posts a thread to magazine M.
User "B" on a different external instance cannot see user A's new thread.
I have encountered this ...
I did some further testing of federation issues, and have discovered that Kbin (at least Fedia) magazine articles don't federate to remote instances unless they are interacted with on the host instance.
YSK: If you own a magazine on Kbin, make a point of interacting with everything (just an upvote is fine) to ensure it gets pushed out and seen, at least until this is fixed.
(that includes this article, can't see it from Lemmy until it gets interacted with on kbin.social!)
Unfortunately, I think that is a innate function of federation. Mastodon is like that as well, you don't start seeing stuff from remote instances until you/someone on your instance starts interacting with it.