Not seeing federation from my pyfed instance.

I set up an instance of pyfed at https://eventhorizondataflow.pagekite.me/ but as far as I can tell it doesn't seem to be federating. Subscribing to communities works initially, but no new content comes through. However, I can manually add new remote posts (and added a quick hack to rebackfill a community to keep up to date).

I also tried posting from my instance to c/playground here but they don't seem to be coming through.

I'm not seeing too much in the logs or in the activity page (under Admins). For posting to c/playground for example, I can see the CREATE activity to piefed.social - that is simply marked as a green success.

Looking for ideas on how to debug this further.