Website activity feed shows default facebook thumbnails in stead of og:image

Question

As the title suggests I am having trouble getting the correct thumbnails in my websites activity feed. When a user likes an article the activity feed works fine and shows the article liked. However it always shows the default facebook thumbnail image.

I have used the facebook debugger and it does not show any errors or warnings and it does show the correct og:image.

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What have I tried

I have tried liking the pages I pulled through the FB debugger to see if a hard refresh would perhaps solve the problem, it did not.
I have tried specifying the articles with article type og:article, in hope i would solve the problem, this did not work either.
I have read through the facebook documentation and I find it very lacking when you are looking for something that does not go as planned, I did not find anything related to the activity feed thumbnails in here.

I think the problem might lay in facebook their image cache, but I'm not entirely sure. I read that there really isn't a way to hard refresh that + I would have to do it for every page/article on the website which is not logical.

Hopefully some of you have had the same problems and can point me in the right direction. Cheers

edit
Here are my meta tags (along with smarty template enginge)

<meta property="og:url" content="http://{$smarty.server.HTTP_HOST}{$smarty.server.REDIRECT_URL}">
<meta property="og:title" content="{$facebook_like_title|default:'*website name*'}">
{if $facebook_like_description|trim != ":"}
<meta property="og:description" content="{$facebook_like_description|default:'*Default like description*'}">
{else}
<meta property="og:description" content="*Default like description*">
{/if}
<meta property="og:image" content="http://{$smarty.server.HTTP_HOST}/img/logo.png">
{if $article}
<meta property="og:type" content="article">
<meta property="article:author" content="123456789"> 
<meta property="article:author" content="123456789">
{else}
<meta property="og:type" content="website">
{/if}
<meta property="og:site_name" content="website.com" />
<meta property="fb:app_id" content="****************" />

FB activity feed:

<div style="background-color: #fff; overflow: hidden; width: 220px; height: 300px; margin-bottom: 20px;">
        <div class="fb-activity" data-site="website.com" data-app-id="*******************" data-width="220" data-height="300" data-header="true" data-border-color="#2F5480" data-font="arial" data-recommendations="false"></div>
</div>

Like button:

<div class="fb-like" data-href="http://{$smarty.server.HTTP_HOST}/{$news->readonUrl}" data-send="false" data-width="400" data-show-faces="false"></div>

Edit 2
Here is a screenshot from the activity feed:

I have removed the first users profile picture (privacy and all that) but it is showing up correctly. The second user has got a default profile picture.

Now what I want is those "filler stories" to have the correct thumbnail (which is specified as the og:image) and not the default one.

Here is an example link which FB should be scraping when liked (first filler story in this case):
http://sportflock.com/food/voedingsschemas
FB lint:
http://developers.facebook.com/tools/debug/og/object?q=http%3A%2F%2Fsportflock.com%2Ffood%2Fvoedingsschemas

Answer 1

The problem eventually solved itself. It must have been the facebook cache or something. After not having checked on this problem for several months, I came to check on it to see if anything had changed. Suddenly all thumbnails showed correctly without any help from my side.