Sadly it seems after all that at present setting
Type ( Electric )
NumWheels ( 0 ) Comment ( * 0 axles powered * )
does have some impact on functionality - it can cause the wheels to rotate in the wrong direction. See this thread.
A temporary work around would be to use something like
Type ( Electric )
NumWheels ( 1 ) Comment ( *imaginary axle required by OR for correct wheel rotation* )
ORTSDriveWheelWeight ( 0 ) Comment ( * 0 axles powered * )
This just seems to reinforce the need to have a properly functioning
Type ( DrivingTrailer )