There is a problem with the supportedThermostatFanModes attribute as reported by your driver, as @jtp10181 guessed above. If there isn't a fix directly available in your driver (I don't have an Ecobee to know for sure), there is a workaround you can do by temporarily setting the driver to Virtual Thermostat and running the setSupportedThermostatFanModes() command and passing in an appropriate value (not necessarily exactly what is in this post, but that's the format you'll need):
Your supportedThermostatModes attribute looks OK, so you can probably ignore that part.
