This is not an unexpected behavior. MoveL_Test requires passing the joints from the start point (first parameter) and the destination pose (second parameter).
I recommend you to take a look at the example attached.
This example creates a cube of targets that are followed by the robot in a program. It tries to use linear movements as much as possible (using MoveL_Test first to validate the linear movement this is possible). Although may want to follow all the points with linear movements, you may hit a singularity, collision or axis limit. Therefore, you may have to change the robot configuration when this happens by using a joint movement (MoveJ) instead of a linear movement (MoveL).
I recommend you to take a look at the example attached.
This example creates a cube of targets that are followed by the robot in a program. It tries to use linear movements as much as possible (using MoveL_Test first to validate the linear movement this is possible). Although may want to follow all the points with linear movements, you may hit a singularity, collision or axis limit. Therefore, you may have to change the robot configuration when this happens by using a joint movement (MoveJ) instead of a linear movement (MoveL).