Thank you all for your feedback!
In the end, I found that the issue: A bad crimp (home made) inside the connector of the endstop to the board..... and the same for the second cable tested..... bad luck or bad crimping skills 
Not visible at first. But now all is back to normal
Best posts made by happycaribou77fr
-
RE: Dual Z homing issue - only one motor movesposted in Duet Hardware and wiring