As an update to the above, Martin sent me additional details about the device and I was able to determine what’s happening.
-
The device implements custom Homey capabilities called
operating_modeandfan_speed. -
The official Homey capability for controlling the Thermostat Mode is called
thermostat_modeand is not implemented on this device which is why the ‘Adjust’ option doesn’t show up.
That being said, Homey users can still interact with custom capabilities as noted here: