A payment gateway is not available for a currency/country
Check that the payment gateway supports payments in this currency. WooCommerce disables the not available payment gateways (for example, when the payment gateway does not support the currency)
Price Based on Country for WooCommerce requires a payment gateway that supports the currencies in which you want to work. For example, if you’re going to work with USD and EUR, you need a payment gateway that supports USD and EUR. Or a payment gateway that supports EUR and another that supports USD.