Make sure you create the folder first and you have rights to write to it.
On my Jetson AGX I have to open the folder once when I start up the computer or else nothing will write to it. The reason being is its and external harddrive. On my other machines I do not have to open it first. As long as the folder exists it writes to it.
Strange it does not run offline. I record the point cloud using ROS on a raspberry pie. Then copy the bag file to another computer. I then launch lidar_mapping in one terminal and rosbag play the file in another. When done playing I close livox_mapping with control C and it saves the file.
I have successfully parsed the point cloud data in *.lvx format into PLY and PCD formats (expandable to various common formats you need). Contact me if necessary, email: www.fxw66697@gmail.com