Several possible faults.
You tell that YOU move tractor to both sides of AB line, and then test, in this situation you should also drive faster than 1 km/h to get reading because AOG turns off under 1km/h!
It is better to test like Brian do in the setup video: AutoSteer Settings From Default Config - YouTube then you should get reading when moving slider in autosteer configuration.
What ino du you use to your Nano setup (i suppose wire setup as the OLD WIKI for IBT_2 )
OLD WIKI wiring does not fit new PCBv2 ino, you must change pin numbers or wiring to make it work!
Also if you use PCBv2 ino you must have a switch/ground to pin PD6 as MylArti told in another thread!
You need to connect the D6 pin to ground. otherwise, the PWM pins D3 and D9 will not output voltage.
in AutosteerPVCBv2.ino setup…
#define SwitchOrButton 0 // set to 0 to use steer switch as switch
// set to 1 to use steer switch as button
// Button/switch pulls pin low to activate
//--------------------------- Switch Input Pins ------------------------
#define STEERSW_PIN 6 //PD6