I believe WC was upgraded overnight (I received email 250am AEDT) and as part of this, there were changes to the MaxMind Geolocate integration, which requires store owners to approve an EULA to use the geolocate service.
Is it possible that the affected customers placed orders after the upgrade took place, but before approving the EULA and as such, geolocate didn’t work so the integration doesn’t recognise that they’re in a stateless country?