Kalman filter estimate drifting

I'm seeking some help to tune the EKF, I'm using https://in.mathworks.com/help/nav/ref/insfilterasync.html this example for asynchronous sensor fusion using discrete EKF from matlab.

I tried with automatic tuning process from matlab example but same issue observed. The EKF does not converge but slowly drifting it's euler estimation from quat. I'm using MPU9250 as an IMU and and GPS data(position+velocity) from UBLOX M8N. Sensors are also calibrated properly.

Here is my matlab code and data file : https://github.com/Saikat-Eng/Async_EKF