I am unable to add a SKU to a product I have listed on my sandbox account. I read on another answer that in order to add a SKU to a product listing, you click on 'Edit > Customize' on the section heading for 'Active Selling'. However, this does not work in the Sandbox. The following CORS error is displaying in the browser console: `Access to XMLHttpRequest at '
https://signin.sandbox.ebay.com/ws/eBayISAPI.dll....' (redirected from '
https://my.sandbox.ebay.com/ws/eBayISAPI.dll...' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.` Please see the attached screenshot [here](