It seems that any Lemmy.world and Lemmy.ml hosted communities aren’t any longer federating properly via kbin as I started getting 404 errors on all of them. Examples:
https://lemmy.world/c/personalfinance: ok
https://kbin.social/m/personalfinance@lemmy.world: 404
https://lemmy.ml/c/fire: ok
https://kbin.social/m/finance@lemmy.ml: 404
https://beehaw.org/c/finance: ok
https://kbin.social/m/finance@beehaw.org: ok
I’m browsing /newest and seeing posts from lemmy.world. The time that OP says the magazine was created on this instance matches when I did my search. I really don’t think the 0.18 thing is what OP is running into (lemmy.world is running 0.18.1-rc.7).