The Working Title GNS 530 unit (see link) seems to be overriding the ability to
GNS
to toggle the GPS DRIVE NAV1 simvar using TOGGLE_GPS_DRIVES_NAV1
It works initially but then as soon as the GNS unit is loaded in, immediately stops working.
This is problematic because the documentation I’ve linked above shows how to setup the CDI for lateral and vertical navigation but the resulting values are way off because the OBS indicators aren’t being updated correctly due to GPS DRIVES NAV1 remaining false even when in GPS mode.