I don't see supportedThermostatFanModes. This is also what Easy Dashboard is telling you. I think it will become a bit less picky in 2.4.0 (unless that already made its way to 2.3.9...i can't remember), although it is technically anseicer problem. To work around this, you could temporarily switch to the Virtual Thermostat driver and use a workaround like this, though just for this particular attribute:
