I have posted to the !evs@lemmy.world community from my lemmy.ml account. However my post does not appear on lemmy.world/c/evs but it does appear on lemmy.ml/c/evs@lemmy.world .
Update
https://github.com/LemmyNet/lemmy/issues/4282#issuecomment-1859947661
Another update
I can confirm that similar things have happened to me recently as a user in lemmy.ml. Don’t know if was a symptom of the beta testing or not though, or whether things are fine now.
It happened multiple times during the 0.19.0 testing phase where federation will break until a new update was being tested. Unfortunately it seems the bug has persisted into final release.
Are the devs aware or have you reported it somewhere? It’s a rather important bug and worth testing to be sure.
I suppose they should notice this post here?
The devs are aware and discussing it here (thanks, it seems, to your post!): https://github.com/LemmyNet/lemmy/issues/4288