On PicSender's 'Probe' screen, there is a probe test feature.
1 - Click the 'Probe Screen' button on PicSender's main screen to open the Probe screen.
2 - Touch the ground clip of your probe cable to the Z probe plate.
3 - Click and hold down your mouse button on 'Test' button under the red 'Z-' arrow.
If your probe wiring is good, the 'Test' button will read "Closed". If the wiring is bad, the button will read "Open".
If you have NOT been using PicSender's probing function, then make sure all the probe screen's 'Setup Values' have the values in them as shown below.
1 - Click the green 'X+' arrow to start the X axis moving to the right.
2 - While the X axis is slowly moving right, manually touch the probe ground clip to the probe plate.
3 - The X axis should stop moving and retract back to the left.
If your testing as above fails, then a bad or broken probe wiring is the most likely cause of your problem.
There are no user settings in grbl to set or change for probing to work. There is only a setting ($6) to reverse probe action from an Open connection to a Closed connection. Your setting should be $6=0 as far as I know for an initial Open connection. I do not have an XController to test with here.