Monit doesn't list WAN interface for network service check

[Ypsilon]

Hi,

When creating a new service setting to monitor link status for WAN, the interface drop down list only lists "none" and "LAN", no WAN.
My OPNsense system is a virtual KVM instance, 2 pass through nics, that are working fine.
ifconfig lists em0 and em1 interfaces nicely.
I already created a similar service setting for LAN (type network), that's working fine.
The monit proces shows it runs like /usr/local/bin/monit -c /usr/local/etc/monitrc{monit}
Opening the /usr/local/etc/monitrc from shell states, so I wont touch it:
# DO NOT EDIT THIS FILE -- OPNsense auto-generated file

So I'm wondering what has to be done to get WAN in the list for Monit.