Unable to make the caching working on the subdomain

I have activated the plugin in the wordpress, which is installed on the subdomain: demo.hobbyhorseslovakia.com.

On the main domain, it is working fine, but on the subdomain it still shows me:

Page caching seems not working for both dynamic and static pages.

Error on dynamic page (https://demo.hobbyhorseslovakia.com): Seem that your website is not behind Cloudflare. If you have recently enabled the cache or it is your first test, wait about 30 seconds and try again because the changes take a few seconds for Cloudflare to propagate them on the web. If the error persists, request support for a detailed check.

Error on static resource (https://demo.hobbyhorseslovakia.com/wp-content/plugins/wp-cloudflare-page-cache/assets/testcache.html): Seem that your website is not behind Cloudflare. If you have recently enabled the cache or it is your first test, wait about 30 seconds and try again because the changes take a few seconds for Cloudflare to propagate them on the web. If the error persists, request support for a detailed check.

Please check if the page caching is working by yourself by surfing the website in incognito mode ’cause sometimes Cloudflare bypass the cache for cURL requests. Reload a page two or three times. If you see the response header?cf-cache-status: HIT, the page caching is working well.

I have also created the page rule in the cloudflare with Cache Everything for https://demo.hobbyhorseslovakia.com/*.

I have tried to clear the cache, deactivate/activate the plugin, but the result is still the same :(.

Can you advice, what shall i do?

I have also activated the debug – this is the result of the test check

[2024-01-19 19:48:22] [cloudflare::page_cache_test] Response Headers: WpOrg\Requests\Utility\CaseInsensitiveDictionary::__set_state(array(
'data' =>
array (
'cache-control' => 's-maxage=31536000, max-age=60',
'x-wp-cf-super-cache' => 'cache',
'x-wp-cf-super-cache-active' => '1',
'x-wp-cf-fallback-cache' => '1',
'x-wp-cf-super-cache-cache-control' => 's-maxage=31536000, max-age=60',
'content-type' => 'text/html; charset=UTF-8',
'content-encoding' => 'gzip',
'vary' => 'Accept-Encoding',
'date' => 'Fri, 19 Jan 2024 18:48:22 GMT',
'platform' => 'hostinger',
'content-security-policy' => 'object-src \'none\'',
'strict-transport-security' => 'max-age=15768000;includeSubdomains',
'x-xss-protection' => '1; mode=block',
'x-content-type-options' => 'nosniff',
'alt-svc' => 'h3=":443"; ma=2592000, h3-29=":443"; ma=2592000, h3-Q050=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q043=":443"; ma=2592000, quic=":443"; ma=2592000; v="43,46"',
),
))
[2024-01-19 19:48:22] [cloudflare::page_cache_test] Start test to https://demo.hobbyhorseslovakia.com/wp-content/plugins/wp-cloudflare-page-cache/assets/testcache.html with headers Array
(
[timeout] => 10
[sslverify] =>
[user-agent] => Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:59.0) Gecko/20100101 Firefox/59.0
[headers] => Array
(
[Accept] => text/html
)

)

[2024-01-19 19:48:22] [cloudflare::page_cache_test] Response Headers: WpOrg\Requests\Utility\CaseInsensitiveDictionary::__set_state(array(
'data' =>
array (
'content-type' => 'text/html',
'last-modified' => 'Mon, 11 Sep 2023 12:51:39 GMT',
'etag' => '"999-64ff0d5b-d5289b011bc1f4c4;gz"',
'accept-ranges' => 'bytes',
'content-encoding' => 'gzip',
'vary' => 'Accept-Encoding',
'content-length' => '1159',
'date' => 'Fri, 19 Jan 2024 18:48:22 GMT',
'server' => 'LiteSpeed',
'platform' => 'hostinger',
'alt-svc' => 'h3=":443"; ma=2592000, h3-29=":443"; ma=2592000, h3-Q050=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q043=":443"; ma=2592000, quic=":443"; ma=2592000; v="43,46"',
),
))