XMLHttpRequest when placing order is being blocked

[watista]

Since I updated my Magento version from 2.3.1 to 2.3.5-p1 the automatic sending of orders isn't working anymore.

Requests aren't received by Trustpilot because the XMLHttpRequest is blocked by the source.

Steps to reproduce:

1. Magento 2.3.5-p1 installation with PHP-7.3 and nginx 1.10.3

2. Trustpilot Magento 2 version 2.6.555

3. Succesfully place order

Expected result:

• Automatic order request is send to Trustpilot and creating an order in de Trustpilot backend

Actual result:

• No request is send to Trustpilot, console log says:
  Access to XMLHttpRequest at 'https://invitejs.trustpilot.com/api//invitation' from origin '[my_website.com]' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

I have no header set that is blocking any requests, I even added add_header Access-Control-Allow-Origin '*'; to my nginx config file but it still didn't work.

Is this an issue on the side of Trustpilot or is the wrong header send with the request? Anyone knows how to fix this?

[tprocter1984]

Any news on this one please? We have had to disable this functionality until this is resolved.