I’ve had similar problems with power fluctuations in workouts:
Controllable: Suito via Bluetooth
Power Source: “Suito” via Bluetooth, not the ANT+/BLE power meter it shows up as
Cadence: Stages PM via ANT+
The workout had a 30s @ 465W sprint then 30s@82W
The 465W wasn’t a problem, the trainer ramped up a bit slowly but I could pedal faster/change gear to get there.
At the end of the interval the power dropped off rapidly like I’d broken my chain and because the flywheel was spinning so fast I couldn’t put out any power. When the trainer had slowed enough to pedal the watts in Zwift were way below 82W, it was screaming at me for more power but the trainer wouldn’t put the resistance back on and by then I’d missed the star and it was onto the next interval.
The workout was 6m @ 246W then 3m @ 150W. At the end of the 246W the resistance dropped off rapidly again and undershot the 150W and in once case went as low at 100W. It got back up to 150W after approx. 20s but then it reduced the resistance again to around 125W before coming back up to 150W. Even though it got to 150W after about a minute, I still missed out on the star.
I’ve tried both keeping the cadence and gear steady, and adjusting gear/cadence to try and get it right but with no luck.
I’ve also had the resistance spiral of doom as another person called it, but the last few times Zwift has been pretty good at spotting it and temporarily disabling ERG until you can get back up to speed again.
Sim mode isn’t bad, although I’ve had to turn the difficulty down low so when I crest a hill it’s not like I’m going over a jump.
I’m not sure if the problem is with Zwift or with the trainer. I guess I need to program the workout into the my e-Training app and see if the same thing happens.
Or maybe I’m just expecting too much from a smart trainer?