Please make sure you have "undetermined" selected in your list of spoken languages in your lemmy settings in addition to any other languages you speak.
Most lemmy content does not come through with a language tag, and you need to have undermined selected as an option to see that content.
🤦 I read this post yesterday then promptly forgot about it and proceeded to unmark "undetermined" in my language settings only to wonder today why I was missing a ton of replies on posts...
...at least I've fixed it now 😅