There's a couple reasons as to why this occurs:
- The tag isn't applied properly to the customer account. Ensure that it EXACTLY the same (capital letters, spaces, etc.) as the tag you created in the "manage tags" section of the app admin.
- The app's code hasn't been installed quite properly or not at all in the theme's files. Ensure that the app's code is installed correctly, particularly in the file that controls the price field on the part of the storefront where the pricing isn't showing correctly (i.e., check the collection.liquid file if the wrong prices are showing on the collection pages).