I found and subscribed to https://sh.itjust.works/c/[email protected] yesterday and when I view it on sh.itjust.works I don't see any posts but on the original instance I'm seeing many posts.
Yeah it's... strange? I don't know if the list of languages exist is something the instance admins pick or if it's a Lemmy thing, but it probably should default to no languages selected so you can see everything. Maybe even when you look at a community and it says "no posts" it should hint at there are posts just not in the languages you've asked to display.
very confusing indeed, anyway thank you for your help! :)