The way eBay works, they have two different elements.
1) Your actual blocked countries list.
2) Your shipping policy that outlines your shipping rates for countries ahead of time.
If you do not add a country to your block countries list, eBay presents it more like the seller will ship to you but they don't have a quote. So you can buy the item and ask them for an invoice.
How do I fix this?
-Top right corner where it says "Hi your name". -> Account settings.
-Click the "selling" drop down on the left side of the screen. Click "Shipping Preferences".
-Scroll down to Rates and Exclusions.
-Click 'edit' on Exclude shipping locations.
You should be able to add the USA to that list from there.
When I do it on mine, it tells me that I've opted into business policies. Presumably, changing my business policies should be sufficient.
Under selling, instead of shipping preferences select business policies. Then open your shipping policies. At the bottom, you should see "excluded locations" with a list of over 200 countries. You should be able to add USA to this list.
Ultimately, it's not a big deal if you get a US order. Unless I am mistaken, cancelling due to problem with address should be valid. Although, it is cleaner to block countries that you don't ship to.
