I think Facebook is unable to access your blog page to get the image from your blog page open graph metadata since your site required user to login first in order to access the blog page.

To test this again, you can allow guest user to access your site blog page then copy one of your existing blog post URL and paste it to the Facebook debugger tool https://developers.facebook.com/tools/debug/ so the Facebook will recrawl to your blog page again.

Hi Arlex,
Thanks for your reply.

Quoted from Arlex Wong on Wednesday, 06 July 2022

I think Facebook is unable to access your blog page to get the image from your blog page open graph metadata since your site required user to login first in order to access the blog page.

Where is this setting? I can't find it:(

Quoted from Arlex Wong on Wednesday, 06 July 2022

To test this again, you can allow guest user to access your site blog page then copy one of your existing blog post URL and paste it to the Facebook debugger tool https://developers.facebook.com/tools/debug/ so the Facebook will recrawl to your blog page again.

Guest are allowed to access. Done this several times but still the same results.

From what I tested, it seems like it only shows the grey blank placeholder in the Facebook share dialog, if I click the share button, the Facebook post still shows the image.

I am not sure whether it is a Facebook bug or not because even if I switch to render the ShareThis social button temporary on your site, then I click the Facebook share button, it shows the same issue, you can watch my attached video below.