The root problem is [`updatePoseFromHostShadow()`](https://github.com/sparkfun/SparkFun_Optical_Tracking_Odometry_Sensor/blob/3501e487bd247fff5e409eeb6b0a7a30b22fb9a8/Firmware/SFE/Src/main.cpp#L569) does not set register contents. That should be done after checking if `allRegsWritten` is true.