Fusion of external library for Quadrature Encoder with EKF3 in Ardurover on BBBlue

I am running Ardurover on BBBlue. I have the Quadrature encoder reading (clockwise/anticlockwise) from external library.
I want to fuse these reading with the EKF for waypoint navigation.
For that i am providing the readings in the following API in sensor.cpp-
EKF3.writeWheelOdom(delta_angle, delta_time, wheel_encoder_last_update_ms[i], g2.wheel_encoder.get_position(i) , g2.wheel_encoder.get_wheel_radius(i));
But not able to see rover moving on the map. Also it does not go according to waypoints. I know Wheelencoder is not currently done in BBBlue.
Can anyone suggest me something to get this? Is the above API only needed to be taken care of?

Just for information, i am not using GPS.