Good news
Just for info config/agent.conf is for allowing commands to run so any parameter in scServer config with a CMD must be allowed. A common obe is snapdrive.
And example for windows snapdrive
command: sdcli.exe
The agent does take a few seconds to start after service starts
Also if you need to troubleshoot agent best thing is running it manually in debug mode
ie: snapcreator.exe --start-agent <port> --verbose --debug
Let us know if you need anymore help
Keith