Anything in the Agent log?
McAfee ePolicy Orchestrator provides log files that contain important information when troubleshooting (page 5 for Agent logs).
How to enable debug logging and collect an event trace log for McAfee Agent 5.x for Windows Technical Articles ID: KB82170 Last Modified: 9/8/2016
You can go to system tree, click on "new systems". Here you can install agents on the correct path. Before doing so, export a list of systems or IP addresses.
You can try creating a server task, with action "run external command".