AeroPod, PowerPod and Newton

Last week I was looking into some of my ride files.
Have a few out/back rides and did some "check calibration"
Every time, if I click "accept", I get the "Your tilt calibration appears to be invalid. Be sure to
do another calibration before yout next ride".
I normally do tilt cals before a ride, or check on my marked spot on the garage floor. My Newton seems pretty accurate
when riding and doing analyzis, and the "check calibration" only cause a slight change. I know I do everything right doing tilt cals, and get "GOOD TILT" in the ibike display. The "riding tilt" comes from my cal ride.

But just to sure I did a new ride, a 100% correct til calibration, but still get the same "invalid" error...

Why do I get this message?

All is well.

In the Check Calibration feature, Isaac is trying to separate out two very similar tilt factors. It is extremely difficult to do this, and sometimes Isaac gets a bit confused.

I occasionally get this message, and I ignore it.