This is through 'jch optimized', too.
The static-url points to the same directory but is a CNAME Record. It is only unsed becaus of cookieless delivery... No speedup setting...

I see,
I think at this point you should manually add the og:tag using this function docs.joomla.org/JDocument/setMetaData and this variable: $this->item->image;

Thank you,

now the og:image-tag ist there, but the image-url is not correct
output:

<meta property=og:image content=$this-&gt;item-&gt;image />

Tested with an without semicolon at the end

i have inserted it into item.php
<?php
$doc =& JFactory::getDocument();
$doc->setMetaData( 'og:image', '$this->item->image;' );
?>

Is should be $this->item->image instead of '$this->item->image;' (remove the quotes and the semicolon)

Ok thanks.
the code is now:


and i get this:


if i change the tag-name to og:image:url it looks like this:

My bad, sorry.
$this->item->image will provide a relative URL, while you need an absolute URL.

Instead of:
$this->item->image

You should use:
'http://yourdomain.com'.$this->item->image

It finally worked, thank you very much!

Nevertheless, it would be interesting to know what is the problem.

Indeed.
If you feel like experimenting, or you have a dev site available,
you can deactivate extensions one by one to see which is causing this issue.