Mr Cammack -
Where are you taking the DOUT signal from? With this device, we put in some logic to align the data with the SCLK output for higher frequency operation in FS mode. You may want to try taking the data from the J2 header which is before the logic (flip-flop U20).
You might want to also try powering down all the channels once all the supplies are up and then back on to see if this helps to resolve the behavior you are seeing.