Issue with store code field for Google Local Products Inventory feed

Hi! I’m trying to create a Google Local Products Inventory feed and having an issue with the store code field. I created the template, used the XML option. I have the store code, but I can’t paste the code into the Value tab. I followed the guide (https://adtribes.io/how-to-add-multiple-store-codes-to-your-google-local-products-inventory-feed/) and probably is outdated because the Value only provides a dropdown menu instead of an empty field to paste the store code into….