1720 error problem resolved. Turns out that the +/-99999999 data that is causing this error is not in NC Comm. as the manual suggested. The data there is the software limits which is not referenced until you have initialized your axis.
When you boot up, the 810M assumes your incremental encoders are at zero and compares that to the data in "Setting Data" -> "Common Axial". In this screen, you need to set your absolute physical min and max work areas. Once entered, reboot the controller and the 1720 errors go away.
Hope this is helping someone out there.