Sorry for the delay in getting back to this. I was able to do the loop-back on both USB-1808X's in question and attached the screen shots from AMI showing basically locked far in to the negative region (0-10V mode or not). Please note: both units go negative immediately on power, never to change.
These were done with another PC using AMI only, though it worries me how one might do this in software only. (please do tell :)
Also, I was able to review the other 4 units I had previously installed, along with another unit (not ordered with these) at Honeywell and they all looked good regardless of which PC I used. One curious note: On power up - all A-outs go to zero, upon setting just ONE of the 2 A-outs, the other will go to whatever it was assigned last. (Is this from ULx or firmware?)
Thanks and let me know what you think or where I can go from here.