I had exactly the same issue again today
ERG is actually working (pedalling faster makes the resistance lighter so the wattage output doesn’t change) and vice versa; the problem is exactly as described - the target wattage is out of sync with the workout.
Another give away is in the last two workouts I’ve done, the final block was a 5-minute warmdown, but, disregarding the fact that the wattage was set wrong for the warmdown, the on screen pop up text read ‘now we’re going to do a 10 minute gradual warmdown’
ERG is actually working, it’s either that the coding for the workouts is wrong so that the Wattage changes at the wrong points, or the workouts have changed and they didn’t correct the coding to match
Windows App, BLE, Kickr Core and Kicr Climb (although I lock the Climb for workouts so that it stays at 0%)