I believe I have resolved the problem. I had to build my own project for the KC705, since it did not exist. There is no documentation on the signal types and buses for the ChipScope signals. So, I used a project from a different evaluation board to build my ChipScope project, but I just discovered the radix of the signal buses did not transfer. I have changed the radix of the ADC buses to Signed Decimal, and all appears to be correct now. Such a rookie mistake.
Ben