"Post results to another form" not working

My Mautic version is: 4.0
My PHP version is: 7.4.15
My Database type and version is: MySQL 8.0.19 for Linux on x86_64


I have the following problem:
I have a form in Mautic that I have embeded in a page in my website.
The form has 3 actions:

  1. Add contact to a segment
  2. Remove the Do Not Contact flag
  3. Post results to another form in my website

The “Post results to another form” action does not work any more.
In version 2 it was working.
After installing the version 3 (clean install) it stopped working.
Tried with versions: 3.2.5, 3.3.3, 3.3.4, 4.0 and it failed every time.

I configured the form to send me a mail in case of failure. I get the following error:

Error message: Client error: POST https://xxxx.yy... resulted in a 410 Gone response: 410 Gone
and after that follows the form data.

I tried everything I found in the support forums and in google.
Nothing worked.

Also, if I add the data from the failure email in Postman, the data is posted successfully.

Thank you in advance