As a dev, Lemmy comments are really difficult to work with and sometimes they go missing. Every app tries to mitigate it their own way, but ultimately we are waiting for Lemmy to improve and have clearer documentation on comments. So to answer your question, it’s probably both a Lemmy and Memmy issue.

Also, if you have bot accounts disabled/hidden in your settings, it also hides bot comments

I think this is a Memmy issue, especially if the original post has been blocked by you or a mod. That’s just my guess, however.

I think it’s mostly a lemmy issue since I’ve seen the instances for other apps have posts complaining about it as well