Tow bar fitted, Lane Assist gone!!

[VRS73]

Hi all

Just changed the trusty B6 estate to a B7 Alltrack estate.
Westfalia tow bar with dedicated wiring harness fitted.
On the way home noticed the Lane Assist was turned off.
I have been through all menus and it has disappeared. The lane assist dash light doesn't even appear when the ignition is switched on.
Is it a simple coding error or is it something else. The manual indicates that side assist is deactivated when a tow bar is fitted but I was driving home without towing.
I will pop back to the fitter tomorrow but anyone have any ideas?

Thanks