IMU calibration issues

Hi I'm going through the self balancing motorbike. Trying to get the bias right (on lesson 6.3) when I first started I was able to get values of theta close to 0. After couple of adjustments got to a point I was very happy with.
Then after sometime I started getting very off results. I noticed that 'IMU calibrated' goes to zero alot. After calibrating by moving the motorbike around pretty soon it goes to zero. :S
Also during the process of calibrating a lot of the fail safe outputs are high and the moment I turn on the inertial wheel and the bike tips a bit fail safe mechanism kicks in. To turn it back again I have to stop the project and run it again which takes ages to load.

Hoping you guys could shed some light on this issue.
Thanks so much