Yup, that’s the same issue I am experiencing.
I have a ticket open with them, but it had a rocky start. I found them quite patronising and they suggested that the piece of electrical tape I placed over the sensor was limiting the data transmission at high power
After a few more ridiculous suggestions on their part I sent them my feedback and finally got an answer I can work with.
Their latest is that if you ramp up your cadence quickly ( I do as I am on a dumb trainer ) and the interval is less than 5 seconds, the PowerBeat cannot keep up. As it measures force and cadence, without the cadence it cannot display power.
I was asked to connect to the Bluetooth on my phone and do some intervals. Man, getting these things to connect to Bluetooth has to be up there with one of the most hit and miss things of all time! Waiting to hear back now.
That all makes sense to me. Except that sometimes I experience these drop outs at lower cadence.
Another factor in the signal reliability is not to have any phone chargers in the area.
I am still annoyed as there is nothing in their documentation that mentions the rapid increase in cadence. That is when I need these sensors to be performing. I hate VO2 Max so want to record every last one of them!!