I would suggest posting a pic of the board top down just so we can double check *second set of eyes*
but being i use this board i cant thing of anything obvious of the top of my head, in the possible chance a bad ground but unsure if this would give the same result as in something more in a constant state change.
im at work on nightshift. but if i can find a screw driver here i shall try n get to my psu and double check or grab a pic.
Possibly a bad board otherwise?
i believe i also use mode1 / P1 so this has always worked perfect for me and never an issue even in testing state of other parts on the car that require me to ignition on and off randomly multiple times within minutes/seconds.