Let's look at the bias. Please add this to your watch window:
drv.adcBias
and when Rs is being identify, halt execution and send me the values you get on drv.adcBias (the entire structure of seven IQ24 values.
Also, maybe you already checked this, but please confirm that you updated the filter pole (663 Hz?) to this define:
#define USER_VOLTAGE_FILTER_POLE_Hz (663.0)
Thanks,
-Jorge