Problem with "Set EKF origin". (Rover with encoders cannot change to GUIDED mode.)

Hello, community. I’m building a rover (Rover 4.0) with wheel encoders and without using GPS. I want to control the rover via “cmd_vel” ROS topic and read “/mavros/local_position/odom”. Before this, the vehicle has to be in GUIDED mode but when I change to GUIDED mode, the message in MP shows that “Flight mode change failed”.

I’ve figured out that I have to “set HOME” and “set EKF origin”(?). Set home is OK since the message shows "Set Home to " but when I click “Set EKF origin here” on MP, nothing happened. The vehicle still disappears from the MP map. I want to know why and how can I set the origin.

Here are my parameters. I’ve followed this tutorial all parameters are set.
nuthasith_param.param (16.3 KB)

HW: Pixhawk4

Thank you!