Can't access some communities on other instances through here, even though I can access other communities on those instances. - eviltoast

Hello! Was hoping to make discuss.online my new home instance, but I’m having trouble accessing some communities on other instances:

They don’t show up in communities search, and trying to go to them directly returns a server error page, with an error message given like:

FetchError: invalid json response body at http://lemmy:8536/api/v3/post/list?community_name=rpgcreation%40ttrpg.network&page=1&limit=20&sort=Active&type_=All

I can access other communities on all of those instances…

… so I know it’s not an issue with them being blocked, but it seems like they’re not being fully federated either?

Anything I can do on my end to further investigate or attempt a workaround?