Issue Apache directive not respected in Ubuntu 18

[RobD1982]

Nginx set as proxy with serving requests to Ubuntu 18.04.5 LTS Product: Plesk Obsidian 18.0.38
Nginx set as proxy with serving requests to Ubuntu 20.04.3 LTS Product: Plesk Obsidian 18.0.38,

I set apache directive:

  Header set Access-Control-Allow-Origin "https://example.org"

In ubuntu 18 does not work until I set this in Nginx too (like prioritare)
In ubuntu 20 exactly the same works perfect, despite nginx as reverse proxy it respect Apache directive.

Nginx directives additional while test are empty while test.

In both Proxy mode is checked to make sure that Apache is used.