This is what they said:
I reviewed the issue extensively. The reason why the dynamic caching of SG Optimizer does not work is caused by a plugin incompatibility issue. Per your request, I created a new site on a subdomain – test.presently.fun
There, I started toggling the plugins one by one and found that the unyson plugin leads to the Dynamic Caching being rendered ineffective. When the unyson plugin is deactivated, your site pages are cached properly:
Ivan-Maznev:~ ivan.maznev$ curl -ILXGET test.presently.fun HTTP/1.1 301 Moved Permanently Server: nginx Date: Wed, 13 May 2020 12:39:27 GMT Content-Type: text/html; charset=iso-8859-1 Content-Length: 235 Connection: keep-alive Location: https://test.presently.fun Host-Header: 6b7412fb82ca5edfd0917e3957f05d89 X-Proxy-Cache: MISS X-Proxy-Cache-Info: W NC:000000 UP:0 HTTP/1.1 301 Moved Permanently Server: nginx Date: Wed, 13 May 2020 12:39:28 GMT Content-Type: text/html; charset=UTF-8 Transfer-Encoding: chunked Connection: keep-alive X-Cache-Enabled: True Expires: Wed, 13 May 2020 13:38:13 GMT Cache-Control: max-age=3600 X-Redirect-By: WordPress Set-Cookie: wpSGCacheBypass=0; expires=Wed, 13-May-2020 11:38:13 GMT; Max-Age=0; path= Location: https://www.test.presently.fun X-Httpd: 1 Host-Header: 8441280b0c35cbc1147f8ba998a563a7 X-Proxy-Cache: HIT HTTP/1.1 200 OK Server: nginx Date: Wed, 13 May 2020 12:39:29 GMT Content-Type: text/html; charset=UTF-8 Transfer-Encoding: chunked Connection: keep-alive Vary: Accept-Encoding X-Cache-Enabled: True Link: <https://www.test.presently.fun/wp-json/>; rel="https://api.w.org/", <https://www.test.presently.fun/>; rel=shortlink Set-Cookie: wpSGCacheBypass=0; expires=Wed, 13-May-2020 11:38:11 GMT; Max-Age=0; path= X-Httpd: 1 Host-Header: 8441280b0c35cbc1147f8ba998a563a7 X-Proxy-Cache: HIT
You can review the and verify the matter on your end and if need be – consult with your personal developer or the developer of the unyson plugin regarding the issue.
Senior Technical Support