Workout mode - Kickr ERG mode power 3-5 watts lower than target

Today I did the SST Workout using the wahoo kickr. The wattage kept on leveling out to approxn 3-5 watts lower than the target on zwift. I tried various cadences and gears (although shouldn’t be required in erg mode) to try to hit and sustain the target wattage.

Is this an issue with Zwift, my Kickr… Or me?

Any ideas on how to resolve this?

Erg lags at times.  I know it says you dont have to be in any particular gear for it to function.

 

But in reality, it is better to be in the most direct transmission of power Largest front ring, smallest cog on your rear.

 

For over under drills i would recommend a gear in the middle of cassette.  To allow the lag to smooth out. 

I forgot to add, once your in a particular gear that works for you, keep this for the duration.