That feed is not /c/cat on lemmy.world, it seems.
I just logged out and logged back in with no change. I’ll clear my cache to see if that helps and will update this post if successful.
Edit: Clearing the cache did not help. Must be a Lemmy API issue?
Yeah noted this with a few other .world communities too. As far as I can tell it’s only doing it with lemmy.world communities for me