Quote Originally Posted by dbltoe View Post
USPS has the shop zone for shipping from and sales tax calculations.

When the Enable Shipping=Billing? is set to false, the system picks Store Pickup.

Could this be strictly do to the USPS setting or Price-LowToHigh?
My guess (and I'll try to reproduce with these now-specified settings) is that having the USPS zone set to 'shop' is what's causing this behavior.