I’d say it’s an issue with lemmy.world, as the federated page lemmy.world/c/communityname@lemmynsfw.com does also show no posts when opened in a browser. Browsing it directly from lemmynsfw.com/c/communityname works.

Edit: It works again now.

If OP had changed anything themself, they would probably not have asked. I do confirm that for me the content of nsfw communities became invisible today.