Try setting the NBO sim voltages to:
0V = AFR 15.1
1V = AFR 14.3

The other programmed voltage/AFR points correspond to CALC.AFR_LC11/2:
0.883V = 10 AFR
4.216V = 20 AFR

If you still have problems, try this:
keep LC-1 green and white isolated from chassis/engine ground...
i.e. have it go directly to the NBO signal low pin and FlashScan pin D.

Green and white don't have to go to chassis/engine ground...
Green is called "analog ground", but a better name would be "analog return"...
White is internally connected to green.