This is a simple software bug. You see, the way Lemmy federates is that updates to a community only federate to instances that have a user subscribed to that community. If you take a community like [email protected], I’m the only person on all of Aussie Zone who subscribed to it. I know it because when I subscribed, we started getting updates from Blahaj.Zone about that community.
A few days ago, I was mistakenly banned from that community. And this caused Blahaj.Zone to stop sending our instance updates on the community. I spoke with the admin of the community and got unbanned, but the unban didn’t federate. The instance will only let us know I’m unbanned if someone here subscribes over there. And I can’t subscribe, because this server thinks I’m banned. It’s a deadlock. If it wasn’t for the ban, I could subscribe and the server would realise there isn’t a ban anymore. But I can’t, because this server thinks there is still a ban.
Ha! That’s a wacky edge case. Federation is instance based though. That explanation only makes sense if no aussie.zone user subscribes to any lemmy.blahaj.zone community. Given the overlap of users (a few blahaj users are regulars on aussie.zone), I have a hard time believing that’s the case.
If the unban still hasn’t federated, try getting their mod to ban/unban again. We’ve had issues with posts in /c/Melbourne getting unpinned for other instances previously. The fix was to pin again, wait a minute or so and unpin.
Yeah, I realised I was wrong when someone else in this thread subscribed. I started seeing the posts on the community update, but not the modlog. I was hoping it would just take a few hours for everything to federate, but no dice. The ban is about to time out in a couple hours anyway, so I think I’ll just wait.
Federation of community content is community based, though, and I can prove it. Take a community that nobody on Aussie Zone is subscribed to, and look at it from Aussie Zone. It’ll look empty. Subscribe, wait ten minutes, refresh the page, and you’ll see the most recent 20 or so posts appear. You can do the experiment with any small or new community that not many people here would know about. Just browse the trending communities thingy on another instance, and look for one with a couple of posts. For example, [email protected] and [email protected] both look empty from Aussie Zone right now. If you subscribe, you’ll start seeing days-old posts appearing. Assuming nobody else from here subscribes to them in the intervening time.