Hi Spencer,
I looked at the website code and it seems that there is no broken HTML and the SKU is added without any HTML wrapper at the end of the product wrapper.
Would you please kindly change the theme from Pro to some default theme such as Twenty Twenty and test and see if it adds the SKU or not?
If it adds the SKU anyway, it is not related to our theme and it is something up with the way you add the setting. If it does not show the SKU, then please kindly get back to us with the URL/USER/PASS of your website using a Secure Note alongside how you add the shortcode so that we can delve into details and find the problem cause.
Thank you.