Facebook Invite on a private website

Hi I have a private network so you have to apply for membership if you want to view content…

I am using Yoast Social for open graph…

The problem I have is open graph is picking up the wrong image for Facebook but I have set all my pages to use stand ogtags which I set on each page…

I used Facebook object debugger to fetch new image but it will not work…

How can I get Facebook object debugger to change the picture…