[MattAustin]

Has anyone refined this Mod as I am finding that if you go through the checkout process and at any stage try to Modify your details, the dropdowns will never be populated.

They will only ever be populated if you log in and then click Modify Profile and then if you switch profile you are taken to Personal details of checkout process (regardless of whether anything is in the cart) and again the dropdowns are empty.
Any help with this is much appreciated