Scope
Validate VAT Number
Billing Country Needed
Billing Country needed to validate the VAT number
Solution
During Checkout, if the Billing fields are hidden, then the Billing Country will not get passed.
This can be fixed by going to your Chargebee Site, and going to Settings -> Configure Chargebee -> Checkout & Self-Serve Portal -> Fields -> Billing and selecting Enable
From there you have to ensure that under Address Fields, Country has been enabled