Resistance only changes when workout has finished

I’ve got a Wahoo Kickr (2016 model) and use Zeift on my Macbook Pro (2016).

The problem I have is that the resistance on my smart trainer doesn’t change going up or downhill but as soon as I finish a workout the resistance kicks in making it much harder to pedal, as it should be when I’m still climbing when the workout stops.

I select Wahoo 456 in the initial set-up for both.

Sounds like you may have disabled ERG mode for workouts, in which case Zwift will keep you on a consistant 1% grade no matter what so you can properly perform the workout.

When choosing a workout, look at the bottom of that window and you should see a checkbox for “Use ERG Mode”.  Check that and you’ll feel the KICKR will help you do your workout properly with varying intensity.