Hello Steven,
Thanks for reaching out to us.
The data entered in Additional Data is not displayed automatically on the product page.
To show this information, please edit your EasyStore -> Single page in SP Page Builder → Pages → EasyStore → Single and add the Specifications addon. This addon is responsible for displaying the Additional Data fields that you enter for each product.
After adding the Specifications addon and saving the page, the additional information should appear on the frontend product page.
Thank you.