Nice job on the schematic! However, it does not show decoupling capacitors on the motors, motor drivers or the sensors. For the sensors, you should have 10uF in parallel with 0.1 uF right across the sensor power terminals. For the drivers, typically 100 uF is used, again right across the motor driver power terminals.
Nothing else really jumps out, except that the DRV8871 driver is inadequate for that motor. The peak driver current is only 3.6A, for a startup current of 3.8A.
Are all your motor and power connections well soldered, with reasonably heavy (16-18) gauge stranded wire?
You may need to borrow an oscilloscope to check for voltage spikes or drops on the power leads.