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

Hi,
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?
Thanks.

Just for information, i am not using GPS.