If they’re new, it might be an issue with the Reddit Hug. From the way I understand it, Kbin has been hit hard by new signups and added extra cloudflair checks to slow everything down in order to keep going while the backend is worked on. That slowness has meant less frequent polling of the fediverse and less caching, so fewer posts are reaching the front page and external instances occasionally don’t show up in search (especially if they’re new).

Not sure if this is the issue you’re seeing on lemmy.dbzer0.com as well, but either way I bet it’s just growing pains. How do you like the fediverse so far?