Just thinking out loud… When you just turn on Kickr Bike without connecting it to Zwift, you can pedal and can switch gears, but my recollection is that resistance remains relatively low. Does it feel the same way when you ride in Zwift and your power remains under 80 watts? If this is the case, I wonder if your trainer got correctly connected to Zwift as a controllable. Zwift might be reading the power you generate correctly, but might not be able to send to the trainer a command to increase resistance. Then, you end up riding with no or little resistance and of course cannot generate any significant power.
Just as a thought, it might be worth disconnecting your trainer from Zwift and connecting it back. When connecting KICKR Bike, you should see the same device name in all three Zwift connections windows: power, cadence, and controllable. If you purchased your trainer just recently, it can be confusing - why three different windows if the same device goes into all of them?
Additionally, it may be worth checking through Wahoo app if you are running the latest firmware of Kickr Bike. This is because connecting protocols keep on being developed and changed.
Finally, consider, as a test, switching to a different connecting protocol, i.e., test ANT+ if you have been using Bluetooth, or the other way around. Perhaps something is not working properly with the protocol which you are using.