The last week, I think I made the start of the breakthrough to the IMU issue. It is possible that the internal pull-up resistor on the RPi is not working. I tried a various combination of external pull-up and pull-down resistors, but the ones I’ve tried so far have not worked. Google gives a conflicting number of answers and the manual I found for the BNO055 didn’t clarify what type of resistor I should use, so I’ll have to look into the issue further.
Just another Carnegie Mellon University: ECE Capstone Projects site