Power Not Controlled with Tacx Flux, Custom Workout, and erg Mode

I am using a Tacx Flux with a custom workout in erg mode. I have it connected to Zwift via Bluetooth on a MacBook Pro. The custom workout has the desired power levels entered however when I’m riding Zwift does not seem to be controlling the resistance/power at all. If I pedal hard thenpower increases if I pedal softer the power decreases. I thought the purpose was to increase/decrease resistance to keep power at the desired value. Zwift does tell me to decrease or increase power but that’s not what I though would happen. 

On the pairing screen in Zwift have you got the Fluz paired both as the power source and also as a controllable trainer?

My friend had this with the Flux. It was because it wasn’t paired as the controllable trainer