Random thumbnails when sharing posts on social media

Hey guys,

So this started happening to me a couple of weeks ago, when i publish a post on my website and try to share it on my facebook page the featured image is the last thing thats coming up on the thumbnail especially if in the post there are other images i either get those or my website’s header image. Even when i use the facebook debugger it shows the featured image but when i try to post it on facebook the thumbnail is not the featured image

Also i have been using the SEO Ultimate plugin that gives you some option on what the social listings will show because sometimes i want the thumbnail to show something other than the featured image maybe a sneak peak and then when you go in see the full thing, that also stopped working.

The website in question is https://www.rezusonline.com