DRV8706-Q1: Current Shunt Operation

Dear Support Team

I am using a DRV8706 to drive a brushed DC motor controlled by an MSP430F5529. I have a 2mR shunt  between SP and SN and am monitoring the  SO pin with an ADC input. I have tried various configurations of the CSA register, but the amplitude on SO remains the same no matter what the load current is through the shunt. The noise obviously increases if I adjust the gain from 10V/V to 80V/V. Please see a scope trace of the SO output - I am pulsing the bridge at 7.782kHz.

From the datasheet, I understood that the SO output would be proportional to the current measured between SP & SN.