Here you will find any important information when you update EU VAT Enhanced for Magento 2
Updating to versions > 1.7
Version 1.7 introduced a new field for the domestic country as well as the shop owners VAT number. You need to make sure that these details are properly configured, as it is one of the factors which is certainly responsible for the descision whether a order gets taxed or not.
The information will be taken from the store address config, as long as there is no domestic country set in the configuration.