Community that used to be federated doesn't appear to be any more

Hi—I subscribed a long time ago to !arctic@lemmy.world, but it no longer shows any posts for me, and doesn't show up in search either. Weirdly, I was able to post there (using the Arctic app, signed in to my feddit.uk account). But I can't see the posts... Any ideas what's up there?

Edit: PICNIC