Thanks for the link. I will try the patch ""we recommend that as long as Magnetometer is 3/3, and Gyroscope is 3/3, the data can be trusted"", but it's not the definitive solution.
I have the same problem that this topic : https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/BNO055-losing-calibration/m-p/16973
It is also a good reference, https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/BNO055-losing-calibration/td-p/16973/pag....
"when you do the system design, you should keep the magnetic sensor away from the magnetic material as well as the big current lines. ", could you check it?