There is a bug where sometimes Orbit, the osquery runtime that we use in the agent, doesn't properly configure itself to run on startup. This results in the Linux device not being able to check in.
You can confirm that this is the issue by running the command
sudo systemctl status orbit.service
If you see either "disabled" or "inactive", please follow the instructions below in The Fix.
Run the two following commands in your terminal on the problem device:
1) Start the Orbit service, so the device will start checking in
sudo systemctl start orbit.service
2) Configure the Orbit service to start on boot
sudo systemctl enable orbit.service