Kitted SKUs calculate a QTY on Hand based on the component with the least amount of stock. But this QTY on hand doesn't transfer across to Warehouse QTY. The POS System pulls in warehouse QTY assigned to the register. Therefore, since the kits do not have any stock in the warehouse, the POS will show 0 quantity, even when all the components are available in that Warehouse/Register.
Interestingly, kits WILL display as available on the website for a particular warehouse/register if all components are available (and conversely, show out of stock if not all components are available) - therefore I'm hoping it would be an easy fix to get NetoPOS to display the QTY of kitted SKUs available at the associated warehouse 
