Monitor reports PO is unknown every 10 minutes

I've upgraded to GW14.0.2 and since the upgrade GWMonitor reports one PO status as unknown every 10 minutes, 5 minutes later it reports ok.

The Admin console doesn't show any state change at all and users are connected fine, so it just seems to be the monitor.

I can access the PO via it's web console without any problems.

I'd appreciate any suggestions on troubleshooting this.