I got my Kickr v6 just recently and noticed some buggy behaviour when doing a workout with it on Zwift.
Setup: Latest Kickr firmware, connected over Wifi, latest Zwift version, workout from TrainingPeaks.
FTP 160W, around 90W when doing endurance (GA1) training.
When doing some GA1 training at 90W in ERG mode, it happens that all of a sudden resistance increases to approx. 180W for no reason. I am not doing anything, neither in the Wahoo app or in Zwift compagnion, nor at the PC with Zwift. Initially I thought it would be because the cadence dropped to low (but I would expect the ERG mode to be disabled and not to be set twice as hard…), but from the TrainingPeaks data I can conclude that it was 70rpm at least.
It can be “fixed” by disabling and instantly reenabling ERG mode in Zwift (via the on-screen menu).
It happened now three to four times to hear and heavily affects training.
We had Elite Direto X and Saris Hammer v3 (in fact, one Saris H3 is running in parallel on the same Zwift version and workout and does not have those issues!) and never had those issues.
Only difference is of course the trainer and the connection (WiFi, but the access point is located 3m away in the same room) and I would expect that case of connection problems ERG mode steps are missed or the reported power has drops but not ERG mode going insane.
I can send workout logs and screenshots of TrainingPeaks if this helps. I would be willing to do further low-level logging if I can enable that somewhere.