Visitor ID service and Cross domain

To begin with, since we implemented visitor ID service (and started using first party cookie for visitor id) our cross domain tracking got f*cked. 

The scenario is

- a visitor lands on www.rackspace.co.uk

- clicks on start a chat button and a new pop up come up

- when a visitor types in something in the chat box event77 fires 

The issue is that now in marketing channels 60% of event77 go to session refresh channel. This would suggest that the chat window sees it as a new session but I maybe it simply sees it as a new visitor with a new ID. Could someone help out as I have no idea how to fix it. 

Thanks for the help!