My lbs sold it to me with the rear mounting interface. ANd it makes it sit in front of the bars. I am waiting for the "front interface" any time soon. WIll let you know. as soon as I receive it.
As described by @Shark58, the cable to the Kix display needs to come from the system controller. The Kiox display should have come with an extra cable that then goes back towards the System controller on the top tube.
It is concerning to me that your LBS did not know that or could not check it...