Max cadence lower than Average Cadence, erratic high max cadence

My gear:

Garmin Edge 1040

Shimano Di2 DuraAce 9200P with power meter

Before my cycling activity I fully charged my Edge 1040, my power meter, and the Di2 battery.  I also zero calibrated the power meter.

Every once in a while my average cadence is higher than the maximum cadence, I also get erratice max cadence readings as high as 250+ cadence which no "normal" human cyclist should be able to pedal...  (this happens on average with 1 out of every 8~10 rides):

https://connect.garmin.com/modern/activity/12161758287

I have opened a Garmin tech support to report the bug.

Any info on why this is happening is appreciated.

Thank you -- Cameron