@ch1cken
I don't know the specifics of kbin. With that said, having spent time trying to understand how "likes/favorites/stars" work between some other non-kbin and non-lemmy platforms, I think the issue is with how likes federate. Likes are pushed, not pulled. When someone "likes/favorites/stars" something, that gets pushed to all the instances that that person follows. It only happens once and the "home server/instance" that created and pushed the content in the first place doesn't repeat the incoming "like/favorite/star" activity back out. That means that unless the person who clicked "like" also happens to be connected directly to everyone else that got the initial post, only the people who got the initial post AND happen to be connected to the person (on a different server. This doesn't apply when it's all on the same server) will see the like show up on the post.