Original explanation here: ZigBee Fan Switch | Project Zephyr (Blue Series) - #425 by kyj
Power is always running to the unit. Fan is controlled by smartthings. Light is controlled by the dumb switch, but requires power to be running to the fan due to internal wiring. So power is always on for both.
And again, the setup itself (which is admittedly odd) was working fine, so that’s not necessarily the issue.