I've tried to connect a NPN sensor (LJ12A3-4-Z/BX), with the signal line on Z_PROBE_IN (and using an external power supply) the behavior is the same:
My code:
; Z-Probe
M558 P5 I1 H2 T7000 R0.3 F360 ; digital mode, NO/NC, delay, speed, not used as axis endstop
G31 X0 Y0 Z-0.45 P25 ; X Y Z offsets. P=debounce interval (The debounce interval in ms smoothes the signal)
M557 X15:375 Y20:320 S30 ; define mesh grid
and when I send G30 command the probe works well (the led is correctly activated when a metallic surface is near the sensor) but the bed doesn't stop.
I'm going crazy with these configurations
But by completely changing the type of sensor, it makes me think that the problem is on the board.
Edit:
my last test was to connect the sensor directly to the scehda, to avoid interference on the cables, but nothing, it doesn't work. The stop sign is completely ignored.