OK, my dopey fault - you did mention the driver board, and i didn't notice...
The switch inputs, IC 15 and 16 are all as you suggested - with high's around 4.86v and lows of 0.06v
The outputs however IC 17 and 18 are the complete opposite of your recommendations ie:
Measured
1L 2H
5L 6H
12H 13L
8H 9L
Thanks
