A customer says their country is missing from the checkout country list. Why?

The address form only lists the countries on Settings → Store Settings → Selling Location that are Enabled. If you have added some countries, any country not on that list, or set to Paused, won't appear.

To add it:

1. Click + Add Country.
2. Pick it from Country. The code and dial code fill in by themselves.
3. Leave Status as Enabled and click Add Country.

Before you do, check you can ship there and charge the right amount, for example with a zone for that country in the Shipping Zone plugin.