I’ve owned a Wahoo KICR Core for two years now (2022 model). I’ve never had a problem with the calibration of it, it seemed to calibrate automatically as it should. But now, after I enabled virtual shifting (this week), I can no longer reach 0 W (or at least it takes several seconds, and I give up waiting for that). When I stop pedalling, the power hovers between 10 W and 20 W. Sometimes it goes first to 0 for a single second, and then jumps back up.
Here you can see an example from today: ZwiftPower - Login
In case you can’t view that, here are some power values reported after I stop pedalling: 0, 14, 19, 20, 14, 18, 16, 13, 12, and then I give up trying to supertuck…
Of course, I could be just a coincidence that this started immediately when I enabled virtual shifting…
I have a 11-speed cassette, and I’m in 7th or 8th gear, not sure about the number of teeth there but it’s around 15. Latest version of Zwift and the Play controller firmware.
I haven’t tried manual calibration yet.