Yeah this is kind of an annoying example of finger pointing between companies IMO.
I switched from BLT to ANT+ and it still wagged all over the place. Doing any workout that has power goals I still get only 1 or 2 stars. Have to focus super hard to pedal smoothly. I think the 3 second smoothing actually makes it harder to control because you don’t get feedback on your input until too late so you are constantly doing the wrong thing. The best way I found was to find a gear and RPM that equalled the requested power and just try to hold that. Still tough.
Then I bought a Garmin Vector 3S power meter pedal and set it to be the power meter (ANT+) and the KICKR as the controlled trainer and things work waaaaaay better. Still fluctuates, but not nearly as much.
I’ll note, that with the normal setup, power fluctuates differently on different days and different parts of the ride. I haveall sorts of theories… sampling frequency on PC/Mac, background processes eating CPU, KICKR not transmitting frequently (but this also is reported on Tacx Neo).
Zwift should publish their tolerances requirements for getting a star on a workout segment (maybe they have?). And they should give you credit for being equally above and below the target if they see your power all over the place with missing data.