Resistance ERG Mode

My last 3 workouts I had problem with resistance in ERG Mode. In the middle of a training stage for no reason my Dare2Ride Fuego 1.0 with Garmin doungle ANT+ on my laptop with Windows 10 gets heavy and doesn’t work properly again, even turning the Controllable off and on again. I had to change to “Incline” via Companion to be able to complete the workout. My Zwift is on the latest version.