FAQ・Graphs aren't being displayed in Mackerel and it seems like data isn't being posted.

First check and see if the mackerel-agent is running or not.
If the agent is running, check to see if the server's time is configured correctly.
- If there is a discrepancy between the configured time and the actual current time, there is possibility that data will not be posted correctly.
There is a short time lag between registering a new host and the first metrics post from that host.