The Kickr feedback feature from Zwift (SIM, not ERG mode, right?) starts out fine on a ride and then it stops working and the Kickr just acts like a regular Trainer (except way low resistance where I can only muster about 200W at a bazillion RPM).
The ERG mode during a workout is fine. Except if I let the power drop to ZERO watts for a short while (or is it let my speed go to zero mph?), the Kickr similarly reverts to Trainer mode until I encounter the next “portal” of the Workout Mode.
Zwift is kinda the whole reason I bought a Kickr!