Bug in the ESXi 6.7 U2 Interface?

Hi,

I've just done a clean install of ESXi 6.7 U2 and created a VM.

From the web interface, when I click from Host->Monitor screen to the Virtual Machines tab I see "Warning" on the status tab.

However, if I click "Refresh", the status changes to "Normal". It stays as normal with multiple refreshes. If I click away from the Virtual Machines tab and come back to it, the Warning returns.

Is this expected behaviour and is there any way I can get more information about the Warning? I've had a look in the interface and can't see anything obviously wrong.

Is this in fact a bug in the interface?

Thanks.