Based on your description, it sounds like the Clients are not receiving notifications of new content or actions. This typically occurs as a result of firewalls (hardware or software) blocking downstream traffic on the BigFix port for either TCP between Relays, or UDP between Relays and Clients. See https://support.hcltechsw.com/csm?sys_kb_id=730339d71bfec8dcc13e748edc4bcbd1&id=kb_article_view for additional information.
Allowing for notifications to be received by the endpoints by configuring firewall rules is generally best, but there are other options as well such as command polling, and more recently persistent connections.