After pressing "Insert into post" window goes blank.

Hi everyone,

So basically I noticed this problem yesterday when I tried to write a post on this site me and few other people run (www.hhunity.org).

Here is the problem, post type is “Image” and basically we upload an image here that shows on top of the post. I can upload it normally, EWWW Image Optimizer optimizes the image as usual and the image is then presented to me. Now comes the problem, when I press “Insert into post” it just goes blank but it used to work, although I didn’t write a post for some time so I don’t know when this problem started.

It looks like other people that work on the site don’t have this problem because a friend managed to create a post yesterday, but it happened few hours before I noticed that it doesn’t work for me. There is no problem in file upload since I can upload images and I can even insert them in the visual editor, but they just don’t work here where I need them to work.

I tried it in different browsers (Chrome, Firefox, Edge) and deleted cache, cookies and even more. I deactivated all plugins on the site and the problem still persisted. I even downloaded WordPress manually and uploaded wp-admin and wp-includes again. All plugins are updated, WP is updated (4.4.2).

I took a few screenshots for you to see here: http://imgur.com/a/uU2ZE

And here is a little snippet of the code that is making trouble:

//store old send to editor function
      window.restore_send_to_editor = window.send_to_editor;
      //overwrite send to editor function
      window.send_to_editor = function(html) {
        imgurl = jQuery('img',html).attr('src');
        img_calsses = jQuery('img',html).attr('class').split(" ");
        att_id = '';
        jQuery.each(img_calsses,function(i,val){
          if (val.indexOf("wp-image") != -1){
            att_id = val.replace('wp-image-', "");
          }
        });

I’m not really good at JavaScript so I can’t really fix this myself that’s why I came here.

Thanks in advance!