The Roll and Pitch calculations are stable the Yaw is constantly incrementing at around 10 degrees per second.

I've done quite a lot of searching. I've implemented a little routine to zero the gryoscope at power up (not temperature compensate right now) but holds the Gryo(x,y,z) at around 0 while stationary on my desk.

The changes haven't made any difference. The Yaw does react to movement in the Yaw plane, but there is an underlying increment of around 10 degrees per second.

Any advice would be greatly welcome as I only bought the M5Stack Grey to use the IMU to implement a rowing stroke meter.