I have the same issue. I use multiple accounts across different servers, and get a different subset of comments across each one. Not sure the solution right now.

Not sure if this is the same problem, but it has been noticed that passing messages between federated instances has been hampered by the way the “worker threads” are currently been done. The big instances are essentially getting overloaded with outbound federation work. Solutions for that are in the works. issue/3230

I’m glad I’m not the only one. I am commenting on this post from my own instance and it says it has 0 replies which I know is wrong. I did only federate with Selfhosted just a few hours ago. Who know how long it will take this post to get back to lemmy.world.

I had a similar problem that ended up having to do with my server’s language settings. I didn’t realize you can select more than just “Undetermined” by holding down shift or ctrl. So everything tagged as English didn’t appear until I went back and fixed it. You can read the whole odyssey here: https://lemmy.ml/post/1205767

Thanks for pointing this out, I am just now realizing I am also missing comments. For example this post, I have 7 comments, but the actual post has 10.

Hopefully it’ll mostly resolve given time. Just like when there was a mass exodus to mastodon, the major thrediverse servers are getting overloaded. This creates delays and it seems even lost messages. From experience I’ve had messages from fedia.io take anywhere from 20-120 minutes to show up on my mastodon. As admins beef up their servers, but also as excitement tones down and there is less enthusiastic usage, hopefully the problem will resolve for the most part.

I’m not sure what causes messages to be lost forever vs. just delayed. Maybe Kbin or Lemmy aren’t quite as robust in that? When mastodon was melting down, messages could take 8+ hours to get through, but they seemed to get through. I think your idea about a resync idea is a great one.