We have used magento 2.1.6 community edition for our project. Recently we upgraded it to magento 2.1.9. This system is a multilingual and multi-currency system. We have a theme based on magento Luma theme. The currency switcher is not working in our theme. So we switched to default Luma theme. There it was working. Then we installed Albanian Language pack for the system. After this the currency switcher is not working in default theme (luma) also. We tried to change the Block location of the switcher to footer but nothing is working. We are using USD, ALL, EUR, INR currencies and are using Fixer.io to import currency rates. All the four currencies are enabled in Admin panel. We checked in the file currency.phtml file in module-directory and found that currency count is coming 0 and no other currency than USD is coming in currency list in currency.phtml.
You can use the Magento 2 GeoIP Switcher Extension to automatically direct customers to the store view in their local language and display prices in their local currencies.
This is the complex of Magento 2 Auto Language and Auto Currency Switcher Extensions which use the same GeoIP database to detect customers' locations. There shouldn't be any issues with the currency or language switchers in case you use this extension and complete all of the settings in the configuration.