Power falls off during intervals

I have a Elite Drivo controlled by the xert android app that I use for Power Sprint Intervals at around 12 seconds. As soon as I get up to the prescribed power at my target cadence (1200watts @ 120-130 rpm) the power falls completely off , a drop off of 800 watts. The only way I can keep the power close is to ramp up the cadence to rpm’s that aren’t even close to what is “real world” and even then it falls off 3-400 watts. Any suggestions?

Doing high power intervals can be a challenge in erg mode. Often best to switch to slope/resistance mode when doing these intervals.