Hi Colm,
Are you talking about the application frontends? Do you see at least the servername? Does the problem occurs for Confluence and/or JIRA? if possible attach a screenshot
Open the agent logs, check if you see the agent is connecting to the EM - if possible attach the agent log and collector log
Also, check in the status console, maybe the agent is being denied (you would need to update the LB xml) or maybe a clamp has been reached (you would need to update apm-events-thresholds-config.xml)
Regards,
Sergio