It should, but I'm not 100% on how. Time to investigate.
EDIT: " least one user in an instance needs to search for a community before it gets fetched. Searching for the community will bring it into the instance and it will fetch a few of the most recent posts without comments. If a user is subscribed to a community, then all of the future posts and interactions are now in-sync."
I'll edit in all of the different formats suggested just in case.