Event Feed is empty

Our Event Feed in Chef Automate is always empty. I suspect we have prohibited whatever communication is needed for the feed events.

Currently, we only allow connections from Chef Server to Chef Automate (not the other way around). Does Chef Automate need to by able to initiate a connection to Chef Server? What else might be necessary?

Does anyone have a pointer to what is needed to get the Event Feed to populate? What communication needs to be allowed?